* c-pragma.c (maybe_apply_renaming_pragma): New.
        (handle_pragma_redefine_extname, pending_redefine_extname): New.
        (handle_pragma_extern_prefix, pragma_extern_prefix): New.
        (init_pragma): Register them.
        * c-pragma.h (maybe_apply_renaming_pragma): Declare.
        * c-decl.c (finish_decl): Call it.
        * cp/decl.c (cp_finish_decl): Likewise.
        * doc/extend.texi: Document the new pragmas.

        * config/alpha/osf.h (CPP_SUBTARGET_SPEC): Add __EXTERN_PREFIX.
        (HANDLE_PRAGMA_EXTERN_PREFIX): New.

        * config/i386/sol2.h (CPP_PREDEFINES): Add __PRAGMA_REDEFINE_EXTNAME.
        (HANDLE_PRAGMA_REDEFINE_EXTNAME): New.
        * config/sparc/sol2.h: Likewise.

        * g++.dg/other/pragma-re-1.C: New.
        * g++.dg/other/pragma-ep-1.C: New.
        * gcc.dg/pragma-re-1.c, gcc.dg/pragma-re-2.c: New.
        * gcc.dg/pragma-ep-1.c, gcc.dg/pragma-ep-2.c: New.
        * gcc.dg/pragma-ep-3.c: New.

From-SVN: r51200