libccrtp version 1.7.1-2ubuntu1 failed to build on amd64 with GCC-4.6/oneiric

libccrtp version 1.7.1-2ubuntu1 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2456630

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/2456630/+files/buildlog_ubuntu-natty-amd64.libccrtp_1.7.1-2ubuntu1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 914 lines into the build log:

libtool: compile: g++ -DHAVE_CONFIG_H -I. -Wall -ansi -pedantic -g -O2 -g -O2 -D_GNU_SOURCE -c rtcppkt.cpp -o rtcppkt.o >/dev/null 2>&1
/bin/bash ../libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H -I. -Wall -ansi -pedantic -g -O2 -g -O2 -D_GNU_SOURCE -c -o source.lo source.cpp
libtool: compile: g++ -DHAVE_CONFIG_H -I. -Wall -ansi -pedantic -g -O2 -g -O2 -D_GNU_SOURCE -c source.cpp -fPIC -DPIC -o .libs/source.o
In file included from source.cpp:45:0:
./ccrtp/sources.h:409:11: error: 'ptrdiff_t' does not name a type
make[4]: *** [source.lo] Error 1
make[4]: Leaving directory `/build/buildd/libccrtp-1.7.1/src'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/build/buildd/libccrtp-1.7.1/src'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/build/buildd/libccrtp-1.7.1/src'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/build/buildd/libccrtp-1.7.1'
make: *** [debian/stamp-makefile-build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110424-0133
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/libccrtp-1.7.1