* toplev.c (main): Call the front-end specific post_options
        hook if one is given.
        * toplev.h (struct_lang_hooks, lang_hooks): New.
        * c-lang.c (c_post_options, lang_hooks): Implement lang_hooks
        for the C front end.
        * cp/decl2.c (cxx_post_options, lang_hooks): Implement
        lang_hooks for the C++ front end.
        * objc/objc-act.c (objc_post_options, lang_hooks): Implement
        lang_hooks for the ObjC front end.
        * f/com.c (lang_hooks): Hooks for the Fortran front end.
        * java/lang.c (lang_hooks): Hooks for the Java front end.

From-SVN: r38757