Use --files-from for msgcat too
Use --files-from for msgcat too

Prevent "filename too long" errors when concatenating a huge number of
files (typically when legacy extractors were involved) by passing the
arguments through a file instead of cmdline.

This was already being done for xgettext, extent the same protection to
Extractor.ConcatCatalogs()'s use of msgcat.

vslavik/poedit,nawawi/poedit,PKRoma/poedit,vslavik/poedit,nawawi/poedit,vslavik/poedit,vslavik/poedit,alexhenrie/poedit,nawawi/poedit,nawawi/poedit,alexhenrie/poedit,alexhenrie/poedit,PKRoma/poedit,PKRoma/poedit,alexhenrie/poedit,nawawi/poedit,PKRoma/poedit,vslavik/poedit,PKRoma/poedit,alexhenrie/poedit