Не пересобирается мир. Это нормально? Что с этим делать?

Собственно, в один прекрасный момент (неудовлетворенный revdep-rebuild) решил сделать emerge -e world (предварительно, emerge -e system прошел успешно). В результате получил (прошу прощения за гигантский выхлоп):

ex-cxx.o: In function `main':
ex-cxx.cpp:(.text+0xd5): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long)'
ex-cxx.cpp:(.text+0x1b9): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long)'
ex-cxx.cpp:(.text+0x1db): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long)'
ex-cxx.cpp:(.text+0x3a9): undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::_Rep::_S_empty_rep_storage'
ex-cxx.cpp:(.text+0x409): undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::_Rep::_S_empty_rep_storage'
ex-cxx.cpp:(.text+0x480): undefined reference to `std::basic_string<char, std::char_traits<char>, std::allocator<char> >::_Rep::_S_empty_rep_storage'
collect2: ld returned 1 exit status
make[4]: *** [ex-cxx] Error 1
make[4]: *** Waiting for unfinished jobs....
libtool: link: x86_64-pc-linux-gnu-gcc -std=gnu99 -O2 -pipe -Wl,-O1 -o ex-client1 ex-client1.o  ./.libs/libexamples.a ../../lib/.libs/libgnutls.so -L/usr/lib64 ../../libextra/.libs/libgnutls-extra.so /var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs/libgnutls.so /usr/lib64/libtasn1.so -lz /usr/lib64/libgcrypt.so /usr/lib64/libgpg-error.so ../../gl/.libs/libgnu.a -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/libextra/.libs
libtool: link: x86_64-pc-linux-gnu-gcc -std=gnu99 -O2 -pipe -Wl,-O1 -o ex-client-tlsia ex-client-tlsia.o  ./.libs/libexamples.a ../../lib/.libs/libgnutls.so -L/usr/lib64 ../../libextra/.libs/libgnutls-extra.so /var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs/libgnutls.so /usr/lib64/libtasn1.so -lz /usr/lib64/libgcrypt.so /usr/lib64/libgpg-error.so ../../gl/.libs/libgnu.a -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/libextra/.libs
libtool: link: x86_64-pc-linux-gnu-gcc -std=gnu99 -O2 -pipe -Wl,-O1 -o ex-serv-anon ex-serv-anon.o  ./.libs/libexamples.a ../../lib/.libs/libgnutls.so -L/usr/lib64 ../../libextra/.libs/libgnutls-extra.so /var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs/libgnutls.so /usr/lib64/libtasn1.so -lz /usr/lib64/libgcrypt.so /usr/lib64/libgpg-error.so ../../gl/.libs/libgnu.a -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/libextra/.libs
libtool: link: x86_64-pc-linux-gnu-gcc -std=gnu99 -O2 -pipe -Wl,-O1 -o ex-serv-pgp ex-serv-pgp.o  ./.libs/libexamples.a ../../lib/.libs/libgnutls.so -L/usr/lib64 ../../libextra/.libs/libgnutls-extra.so /var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs/libgnutls.so /usr/lib64/libtasn1.so -lz /usr/lib64/libgcrypt.so /usr/lib64/libgpg-error.so ../../gl/.libs/libgnu.a -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/lib/.libs -Wl,-rpath -Wl,/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/libextra/.libs
make[4]: Leaving directory `/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/doc/examples'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/doc'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5/doc'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5'
make: *** [all] Error 2
 * ERROR: net-libs/gnutls-2.8.5 failed:
 *   emake failed
 * 
 * Call stack:
 *     ebuild.sh, line   54:  Called src_compile
 *   environment, line 2876:  Called _eapi2_src_compile
 *     ebuild.sh, line  646:  Called die
 * The specific snippet of code:
 *   		emake || die "emake failed"
 * 
 * If you need support, post the output of 'emerge --info =net-libs/gnutls-2.8.5',
 * the complete build log and the output of 'emerge -pqv =net-libs/gnutls-2.8.5'.
 * The complete build log is located at '/var/tmp/portage/net-libs/gnutls-2.8.5/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/net-libs/gnutls-2.8.5/temp/environment'.
 * S: '/var/tmp/portage/net-libs/gnutls-2.8.5/work/gnutls-2.8.5'

Будучи парнем не из робкого десятка я запустил emerge --resume и получил такую гадость:

stltest.o: In function `main':
stltest.cpp:(.text+0x501): undefined reference to `std::_Rb_tree_increment(std::_Rb_tree_node_base*)'
stltest.cpp:(.text+0x5fb): undefined reference to `std::_Rb_tree_decrement(std::_Rb_tree_node_base*)'
stltest.cpp:(.text+0x63b): undefined reference to `std::_Rb_tree_decrement(std::_Rb_tree_node_base*)'
stltest.cpp:(.text+0x67b): undefined reference to `std::_Rb_tree_decrement(std::_Rb_tree_node_base*)'
stltest.o: In function `std::_Rb_tree<int, std::pair<int const, double>, std::_Select1st<std::pair<int const, double> >, std::less<int>, std::allocator<std::pair<int const, double> > >::_M_insert_(std::_Rb_tree_node_base const*, std::_Rb_tree_node_base const*, std::pair<int const, double> const&)':
stltest.cpp:(.text._ZNSt8_Rb_treeIiSt4pairIKidESt10_Select1stIS2_ESt4lessIiESaIS2_EE10_M_insert_EPKSt18_Rb_tree_node_baseSB_RKS2_[std::_Rb_tree<int, std::pair<int const, double>, std::_Select1st<std::pair<int const, double> >, std::less<int>, std::allocator<std::pair<int const, double> > >::_M_insert_(std::_Rb_tree_node_base const*, std::_Rb_tree_node_base const*, std::pair<int const, double> const&)]+0x6a): undefined reference to `std::_Rb_tree_insert_and_rebalance(bool, std::_Rb_tree_node_base*, std::_Rb_tree_node_base*, std::_Rb_tree_node_base&)'
collect2: ld returned 1 exit status
make: *** [stl] Error 1
STL disabled.
STL support cannot be enabled due to functionality tests!
 Turn on verbose messaging (-v) to ./configure to see the final report.
 If you believe this message is in error you may use the continue
 switch (-continue) to ./configure to continue.
 * ERROR: x11-libs/qt-core-4.5.3-r2 failed:
 *   ./configure failed
 * 
 * Call stack:
 *     ebuild.sh, line   54:  Called src_configure
 *   environment, line 3512:  Called qt4-build_src_configure
 *   environment, line 3157:  Called die
 * The specific snippet of code:
 *       ./configure ${myconf} || die "./configure failed";
 * 
 * If you need support, post the output of 'emerge --info =x11-libs/qt-core-4.5.3-r2',
 * the complete build log and the output of 'emerge -pqv =x11-libs/qt-core-4.5.3-r2'.
 * The complete build log is located at '/var/tmp/portage/x11-libs/qt-core-4.5.3-r2/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/x11-libs/qt-core-4.5.3-r2/temp/environment'.
 * S: '/var/tmp/portage/x11-libs/qt-core-4.5.3-r2/work/qt-x11-opensource-src-4.5.3'

Насколько я понимаю, проблемы связаны между собой. Как с ними бороться? Почему раньше то собиралось, а сейчас не хочет?

Заранее благодарен.