This is a semi-automatic report based on the latest archive rebuild results [1].
Apologies if it reaches you in error.
Excerpt from the buildlog:
/usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.a(locale.o): In function `__gnu_cxx::__scoped_lock::~__scoped_lock()':
(.text._ZN9__gnu_cxx13__scoped_lockD2Ev[_ZN9__gnu_cxx13__scoped_lockD5Ev]+0xa): undefined reference to `pthread_mutex_unlock'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.a(locale.o): In function `std::locale::_Impl::_M_install_cache(std::locale::facet const*, unsigned int)':
(.text._ZNSt6locale5_Impl16_M_install_cacheEPKNS_5facetEj+0x20): undefined reference to `pthread_mutex_lock'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.a(locale.o): In function `std::locale::_Impl::_M_install_cache(std::locale::facet const*, unsigned int)':
(.text._ZNSt6locale5_Impl16_M_install_cacheEPKNS_5facetEj+0x40): undefined reference to `pthread_mutex_unlock'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.a(locale_init.o): In function `std::locale::locale()':
(.text._ZNSt6localeC2Ev+0x26): undefined reference to `pthread_mutex_lock'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.a(locale_init.o): In function `std::locale::locale()':
(.text._ZNSt6localeC2Ev+0x50): undefined reference to `pthread_mutex_unlock'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.a(locale_init.o): In function `std::locale::global(std::locale const&)':
(.text._ZNSt6locale6globalERKS_+0x18): undefined reference to `pthread_mutex_lock'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.a(locale_init.o): In function `std::locale::global(std::locale const&)':
(.text._ZNSt6locale6globalERKS_+0x6e): undefined reference to `pthread_mutex_unlock'
collect2: ld returned 1 exit status
make[3]: *** [pp_popcon_cnt.static] Error 1
make[3]: Leaving directory `/build/buildd/pp-popularity-contest-1.0.4/src'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/build/buildd/pp-popularity-contest-1.0.4'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/build/buildd/pp-popularity-contest-1.0.4'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20120215-0528
FAILED [dpkg-buildpackage died]
The full buidlog can be found at https://launchpad.net/ubuntu/+archive/test-rebuild-20120201/+build/3166974/+files/buildlog_ubuntu-precise-armhf.pp-popularity-contest_1.0.4-1_FAILEDTOBUILD.txt.gz.
[1] http://people.ubuntuwire.org/~wgrant/rebuild-ftbfs-test/test-rebuild-20120201-precise.html
This is fixed in the current Ubuntu development release.
Precise is EoL, setting task to Won't Fix.