cytadela version 1.0.1-1 failed to build on amd64 with GCC-4.6/oneiric

cytadela version 1.0.1-1 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2448066

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/2448066/+files/buildlog_ubuntu-natty-amd64.cytadela_1.0.1-1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 1701 lines into the build log:

/build/buildd/cytadela-1.0.1/src/videoplayer.cpp:181: undefined reference to `SDL_Delay'
/build/buildd/cytadela-1.0.1/src/videoplayer.cpp:183: undefined reference to `SDL_UpperBlit'
/build/buildd/cytadela-1.0.1/src/videoplayer.cpp:198: undefined reference to `SDL_DestroyMutex'
/build/buildd/cytadela-1.0.1/src/videoplayer.cpp:199: undefined reference to `SDL_FreeSurface'
/build/buildd/cytadela-1.0.1/src/videoplayer.cpp:200: undefined reference to `SDL_FreeSurface'
videoplayer.o: In function `unlock':
/build/buildd/cytadela-1.0.1/src/videoplayer.cpp:54: undefined reference to `SDL_mutexV'
collect2: ld returned 1 exit status
make[2]: *** [cytadela] Error 1
make[2]: Leaving directory `/build/buildd/cytadela-1.0.1/src'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/build/buildd/cytadela-1.0.1'
dh_auto_build: make -j1 returned exit code 2
make: *** [build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110422-0015
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/cytadela-1.0.1