lordsawar version 0.1.8-1 failed to build on amd64 with GCC-4.6/oneiric

lordsawar version 0.1.8-1 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2461178

Details about the rebuild:
https://lists.ubuntu.com/archives/ubuntu-devel/2011-April/033042.html

Direct link to the build log: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2461178/+files/buildlog_ubuntu-natty-amd64.lordsawar_0.1.8-1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 2721 lines into the build log:

../../src/.libs/liblordsawar.a(CreateScenario.o): In function `CreateScenario::addNeutral(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, unsigned int, Gdk::Color, int)':
/build/buildd/lordsawar-0.1.8/src/CreateScenario.cpp:232: undefined reference to `Gdk::Color::Color(Gdk::Color const&)'
/build/buildd/lordsawar-0.1.8/src/CreateScenario.cpp:232: undefined reference to `Gdk::Color::~Color()'
/build/buildd/lordsawar-0.1.8/src/CreateScenario.cpp:232: undefined reference to `Gdk::Color::~Color()'
collect2: ld returned 1 exit status
make[4]: *** [lordsawar-pbm] Error 1
make[4]: Leaving directory `/build/buildd/lordsawar-0.1.8/src/pbm'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/build/buildd/lordsawar-0.1.8/src'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/build/buildd/lordsawar-0.1.8'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/build/buildd/lordsawar-0.1.8'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110424-1255
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/lordsawar-0.1.8