Should check for untranslatable strings in header files as well

[Guillaume Desmottes]

If I add some translatable strings to a .c file and forgot to add this file to POTFILES.in, I'm warned by this kind of message when running 'make check':

The following files contain translations and are currently not in use. Please
consider adding these to the POTFILES.in file, located in the po/ directory.

libempathy-gtk/empathy-search-bar.c

If some of these files are left out on purpose then please add them to
POTFILES.skip instead of POTFILES.in. A file 'missing' containing this list
of left out files has been written in the current directory.
Please report to http://bugzilla.gnome.org/browse.cgi?product=empathy
if [ -r missing -o -r notexist ]; then \
  exit 1; \
fi

That's a great feature. But I just noticed that some strings were not translatable because they were in a .h file:
#define EMPATHY_ROSTER_MODEL_GROUP_TOP_GROUP _("Top Contacts")

It would be cool if header files were checked as well, preventing such issues.