ldapdns version 2.06-3.4 failed to build on amd64 with GCC-4.6/oneiric

ldapdns version 2.06-3.4 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2456100

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/2456100/+files/buildlog_ubuntu-natty-amd64.ldapdns_2.06-3.4_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 385 lines into the build log:

Testing C compiler: gcc-pthread (gcc)
Checking for syslog support: ok
Checking for memzero: bzero
Checking for memcpy: ok
Checking for IPV6 support: ok
Checking for setsid() support: ok
Checking for poll() support: ok
Checking for waitpid() support: ok
Checking for POSIX threads: ok
Checking for non-portable pthreads extensions: none
Checking OpenLDAP dependencies: no idea
make[1]: *** [Makefile.config] Error 1
make[1]: Leaving directory `/build/buildd/ldapdns-2.06/build-tree/ldapdns-2.06'
make: *** [debian/build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110424-0019
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/ldapdns-2.06