* tools/po/po-update.sh: Run msgmerge twice, to avoid spurious diffs caused by     msgmerge's odd behaviour.
* tools/po/po-update.sh: Run msgmerge twice, to avoid spurious diffs caused by
    msgmerge's odd behaviour.

Suggested by: nori

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion