ja translatioon breaks xfwm4 build in trunk

[Olivier Fourdan]

msgmerge: ja.po: warning: Charset missing in header.
                          Message conversion to user's charset will not
work.
ja.po:11:2: parse error
ja.po:11: keyword "mine" unknown
ja.po:15: keyword "r17222" unknown
msgmerge: found 3 fatal errors
msgfmt: error while opening "/usr/src/svn/xfwm4/trunk/po/ja.new.po" for
reading: No such file or directory
mv: cannot stat `/usr/src/svn/xfwm4/trunk/po/ja.new.po': No such file or
directory
msgmerge for ja.po failed: cannot
move /usr/src/svn/xfwm4/trunk/po/ja.new.po to ja.po
make[1]: *** [update-po] Error 1
make[1]: Leaving directory `/usr/src/svn/xfwm4/trunk/po'
make: *** [distdir] Error 1