plotdrop version 0.5.2-3 failed to build on amd64 with GCC-4.6/oneiric

plotdrop version 0.5.2-3 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2465293

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/2465293/+files/buildlog_ubuntu-natty-amd64.plotdrop_0.5.2-3_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 1460 lines into the build log:

/build/buildd/plotdrop-0.5.2/droplist.c:917: undefined reference to `g_free'
/build/buildd/plotdrop-0.5.2/droplist.c:920: undefined reference to `gtk_dialog_get_type'
/build/buildd/plotdrop-0.5.2/droplist.c:920: undefined reference to `g_type_check_instance_cast'
/build/buildd/plotdrop-0.5.2/droplist.c:920: undefined reference to `gtk_dialog_run'
/build/buildd/plotdrop-0.5.2/droplist.c:921: undefined reference to `gtk_file_chooser_get_type'
/build/buildd/plotdrop-0.5.2/droplist.c:921: undefined reference to `g_type_check_instance_cast'
/build/buildd/plotdrop-0.5.2/droplist.c:921: undefined reference to `gtk_file_chooser_get_filenames'
/build/buildd/plotdrop-0.5.2/droplist.c:926: undefined reference to `g_free'
/build/buildd/plotdrop-0.5.2/droplist.c:929: undefined reference to `g_slist_free'
/build/buildd/plotdrop-0.5.2/droplist.c:932: undefined reference to `gtk_widget_destroy'
collect2: ld returned 1 exit status
make[1]: *** [plotdrop] Error 1
make[1]: Leaving directory `/build/buildd/plotdrop-0.5.2'
make: *** [build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110425-1525
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/plotdrop-0.5.2