qt/moc segfaults on FreeBSD 10 ia64

I'm having multiple issues which
point to some problems with qt/moc.

For example, kde phonon build fails
at moc stage:

[ 64%] Built target phonon
/usr/bin/make -f phonon/experimental/CMakeFiles/phononexperimental_automoc.dir/build.make phonon/experimental/CMakeFiles/phononexperimental_automoc.dir/depend
cd /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0 && /usr/local/bin/cmake -E cmake_depends "Unix Makefiles" /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0 /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0/phonon/experimental /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0 /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0/phonon/experimental /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0/phonon/experimental/CMakeFiles/phononexperimental_automoc.dir/DependInfo.cmake
Scanning dependencies of target phononexperimental_automoc
/usr/bin/make -f phonon/experimental/CMakeFiles/phononexperimental_automoc.dir/build.make phonon/experimental/CMakeFiles/phononexperimental_automoc.dir/build
cd /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0/phonon/experimental && /usr/local/bin/automoc4 /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0/phonon/experimental/phononexperimental_automoc.cpp /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0/phonon/experimental /wrkdirs/usr/ports/multimedia/phonon/work/phonon-4.6.0/phonon/experimental /usr/local/bin/moc-qt4 /usr/local/bin/cmake
Generating moc_avcapture.cpp

• • • Signal 11

The full log:
http://eis.bris.ac.uk/~mexas/phonon-4.6.0_1.log

I submitted a bug report to phonon folk,
who tell me it's nothing to do with phonon,
but likely with qt/moc:
https://bugs.kde.org/show_bug.cgi?id=325841

Sometimes automoc segfaults too.

I'm not sure how to pinpoint the exact problem.
Please advise

The kde folk suggest to "try to build without experimental".
I'm not sure what this refers to.