llvm-2.7 version 2.7-6ubuntu1 failed to build on i386

llvm-2.7 version 2.7-6ubuntu1 failed to build on i386
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2461070

Direct link to the build log: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2461070/+files/buildlog_ubuntu-natty-i386.llvm-2.7_2.7-6ubuntu1_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 1830 lines into the build log:

                 from /build/buildd/llvm-2.7-2.7/lib/Support/APFloat.cpp:17:
/build/buildd/llvm-2.7-2.7/include/llvm/ADT/SmallVector.h:110:11: error: 'ptrdiff_t' does not name a type
In file included from /build/buildd/llvm-2.7-2.7/include/llvm/ADT/FoldingSet.h:20:0,
                 from /build/buildd/llvm-2.7-2.7/lib/Support/APInt.cpp:18:
/build/buildd/llvm-2.7-2.7/include/llvm/ADT/SmallVector.h:110:11: error: 'ptrdiff_t' does not name a type
/bin/rm: cannot remove `/build/buildd/llvm-2.7-2.7/build-llvm/lib/Support/Release-Asserts/APFloat.d.tmp': No such file or directory
make[2]: *** [/build/buildd/llvm-2.7-2.7/build-llvm/lib/Support/Release-Asserts/APFloat.o] Error 1
make[2]: *** Waiting for unfinished jobs....
/bin/rm: cannot remove `/build/buildd/llvm-2.7-2.7/build-llvm/lib/Support/Release-Asserts/APInt.d.tmp': No such file or directory
make[2]: *** [/build/buildd/llvm-2.7-2.7/build-llvm/lib/Support/Release-Asserts/APInt.o] Error 1
make[2]: Leaving directory `/build/buildd/llvm-2.7-2.7/build-llvm/lib/Support'
make[1]: *** [all] Error 1
make[1]: Leaving directory `/build/buildd/llvm-2.7-2.7/build-llvm'
make: *** [/build/buildd/llvm-2.7-2.7/debian/stamps/build-stamp-llvm] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110415-0226
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/llvm-2.7-2.7