ne version 2.1-1 failed to build on amd64 with GCC-4.6/oneiric

ne version 2.1-1 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2463018

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/2463018/+files/buildlog_ubuntu-natty-amd64.ne_2.1-1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 365 lines into the build log:

cc -D_GNU_SOURCE -D__USE_GNU -DSTDC_HEADERS -Dinline=__inline__ -O3 -DNDEBUG -c -o term.o term.c
cc -D_GNU_SOURCE -D__USE_GNU -DSTDC_HEADERS -Dinline=__inline__ -O3 -DNDEBUG -c -o undo.o undo.c
cc -D_GNU_SOURCE -D__USE_GNU -DSTDC_HEADERS -Dinline=__inline__ -O3 -DNDEBUG -c -o utf8.o utf8.c
cc -lm -Wl,-Bsymbolic-functions actions.o ansi.o autocomp.o buffer.o clips.o cm.o command.o display.o edit.o errors.o exec.o ext.o hash.o help.o input.o inputclass.o keys.o menu.o names.o navigation.o ne.o prefs.o regex.o request.o search.o signals.o streams.o support.o syn_hash.o syn_regex.o syn_utf8.o syn_utils.o syntax.o term.o undo.o utf8.o -lcurses -o ne
menu.o: In function `draw_status_bar':
menu.c:(.text+0x11f6): undefined reference to `floor'
menu.c:(.text+0x13a1): undefined reference to `floor'
collect2: ld returned 1 exit status
make[2]: *** [ne] Error 1
make[2]: Leaving directory `/build/buildd/ne-2.1/src'
dh_auto_build: make -j1 -Wall -C src PREFIX=/usr NE_GLOBAL_DIR=/usr/share/ne returned exit code 2
make[1]: *** [override_dh_auto_build] Error 2
make[1]: Leaving directory `/build/buildd/ne-2.1'
make: *** [build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110424-2313
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/ne-2.1