[3/7] Preprocessor macro loc

https://gcc.gnu.org/ml/gcc-patches/2018-10/msg02039.html
	* include/cpplib.h (cpp_macro_definition_location): Make inline.
	* macro.c (warn_of_redefinition): Fix comments, examine macro
	type, use C++ for.
	(cpp_macro_definition_location): Don't define here.

From-SVN: r265688