PR macros/13205:

	PR macros/13205:
	* macrotab.h: (macro_define_special): Declare.
	(enum macro_special_kind): New.
	(struct macro_definition) <argc, replacement>: Update comments.
	* macrotab.c (new_macro_definition): Unconditionally set 'argc'.
	(macro_define_object_internal): New function.
	(macro_define_object): Use it.
	(macro_define_special): New function.
	(fixup_definition): New function.
	(macro_lookup_definition, foreach_macro_in_scope)
	(foreach_macro): Use fixup_definition.
	* macroexp.h (macro_stringify): Declare.
	* macroexp.c (free_buffer_return_text): New function.
	(stringify): Constify "arg".
	(macro_stringify): New function.
	* dwarf2read.c (macro_start_file): Call macro_define_special.
testsuite
	* gdb.base/macscp1.c (macscp_expr): Add comment.
	* gdb.base/macscp.exp: Test __FILE__ and __LINE__.