pload version 0.9.5-4 failed to build on amd64 with GCC-4.6/oneiric

pload version 0.9.5-4 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2465288

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/2465288/+files/buildlog_ubuntu-natty-amd64.pload_0.9.5-4_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 518 lines into the build log:

/build/buildd/pload-0.9.5/pload.c:559: undefined reference to `XtAddEventHandler'
pload.o: In function `CheckForWMExit':
/build/buildd/pload-0.9.5/pload.c:590: undefined reference to `XtWidgetToApplicationContext'
/build/buildd/pload-0.9.5/pload.c:590: undefined reference to `XtDestroyApplicationContext'
pload.o:(.data+0x3f0): undefined reference to `XtStrings'
pload.o:(.data+0x400): undefined reference to `XtStrings'
pload.o:(.data+0x418): undefined reference to `XtStrings'
pload.o:(.data+0x420): undefined reference to `XtStrings'
pload.o:(.data+0x430): undefined reference to `XtStrings'
pload.o:(.data+0x448): more undefined references to `XtStrings' follow
collect2: ld returned 1 exit status
make[1]: *** [pload] Error 1
make[1]: Leaving directory `/build/buildd/pload-0.9.5'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110425-1523
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/pload-0.9.5