introduce {class,type}_of_this_parm functions
	* cp-tree.h (type_of_this_parm, class_of_this_parm): New functions.
	* call.c (standard_conversion): Call class_of_this_parm.
	* cxx-pretty-print.c (pp_cxx_implicit_parameter_type): Likewise.
	(pp_cxx_direct_abstract_declarator): Likewise.
	* decl2.c (change_return_type): Likewise.
	(cp_reconstruct_complex_type): Likewise.
	* error.c (dump_type_suffix, dump_function_decl): Likewise.
	* mangle.c (write_function_type): Likewise.
	* pt.c (unify): Likewise.
	* typeck.c (merge_types, type_memfn_quals): Likewise.
	* decl.c (build_this_parm): Call type_of_this_parm.

From-SVN: r173496