libcpp/
        * directives.c (lex_macro_node_from_str): New.
        (cpp_push_definition, cpp_pop_definition): New.
        * include/cpplib.h (cpp_push_definition, cpp_pop_definition): Declare.
gcc/
        * c-pragma.c (struct def_pragma_macro_value): New.
        (struct def_pragma_macro): New.
        (pushed_macro_table): New.
        (dpm_hash, dpm_eq): New.
        (handle_pragma_push_macro, handle_pragma_pop_macro): New.
        (init_pragma): Install them.
        * doc/tm.texi (HANDLE_PRAGMA_PUSH_POP_MACRO): New.

Co-Authored-By: Kai Tietz <kai.tietz@onevision.com>

From-SVN: r123370