einstein version 2.0.dfsg.2-7 failed to build on amd64 with GCC-4.6/oneiric

einstein version 2.0.dfsg.2-7 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2449240

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/2449240/+files/buildlog_ubuntu-natty-amd64.einstein_2.0.dfsg.2-7_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 1551 lines into the build log:

lexal.h:18:9: warning: 'typedef' was ignored in this declaration [enabled by default]
In file included from msgformatter.cpp:2:0:
table.h:21:9: warning: 'typedef' was ignored in this declaration [enabled by default]
g++ -lz main.o compressor.o unicode.o streams.o lexal.o table.o convert.o buffer.o format.o messages.o msgformatter.o -o mkres
compressor.o: In function `pack':
/build/buildd/einstein-2.0.dfsg.2/mkres/compressor.cpp:166: undefined reference to `deflateInit_'
/build/buildd/einstein-2.0.dfsg.2/mkres/compressor.cpp:168: undefined reference to `deflate'
/build/buildd/einstein-2.0.dfsg.2/mkres/compressor.cpp:170: undefined reference to `deflateEnd'
collect2: ld returned 1 exit status
make[2]: *** [mkres] Error 1
make[2]: Leaving directory `/build/buildd/einstein-2.0.dfsg.2/mkres'
make[1]: *** [einstein] Error 2
make[1]: Leaving directory `/build/buildd/einstein-2.0.dfsg.2'
make: *** [debian/stamp-makefile-build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110422-0958
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/einstein-2.0.dfsg.2