gcc.c (default_compilers): Add info about ".mm", ".M" and ".mii" Objective-C++ extensions.

[gcc/ChangeLog]
2004-08-18  Ziemowit Laski  <zlaski@apple.com>

        * gcc.c (default_compilers): Add info about ".mm", ".M" and ".mii"
        Objective-C++ extensions.
        * gengtype.c (get_file_basename): Match entire subdirectory name
        ('cp', 'objc', 'objcp') rather than just its suffix.
        (get_base_file_bitmap): Allow for files to belong to more than one
        language.
        (get_output_file_with_visibility): Treat objc/objc-act.h as a header
        used by more than one front-end.

From-SVN: r86167