fdm version 1.6-4 failed to build on amd64 with GCC-4.6/oneiric

fdm version 1.6-4 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2449797

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/2449797/+files/buildlog_ubuntu-natty-amd64.fdm_1.6-4_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 1157 lines into the build log:

/build/buildd/fdm-1.6/deliver-mbox.c:226: undefined reference to `gzclose'
pop3-common.o: In function `pop3_state_connected':
/build/buildd/fdm-1.6/pop3-common.c:391: undefined reference to `MD5'
imap-common.o: In function `imap_base64_encode':
/build/buildd/fdm-1.6/imap-common.c:211: undefined reference to `__b64_ntop'
imap-common.o: In function `imap_base64_decode':
/build/buildd/fdm-1.6/imap-common.c:227: undefined reference to `__b64_pton'
imap-common.o: In function `imap_state_cram_md5_auth':
/build/buildd/fdm-1.6/imap-common.c:431: undefined reference to `EVP_md5'
/build/buildd/fdm-1.6/imap-common.c:431: undefined reference to `HMAC'
collect2: ld returned 1 exit status
make[1]: *** [fdm] Error 1
make[1]: Leaving directory `/build/buildd/fdm-1.6'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110422-1352
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/fdm-1.6