re PR c++/26912 (friend const member function specialization fails to compile)

re PR c++/26912 (friend const member function specialization fails to compile)

	PR c++/26912
	* cp-tree.h (build_this_parm): Declare.
	(grok_method_quals): Remove.
	(build_memfn_type): Declare.
	(build_artificial_parm): Declare.
	(do_friend): Remove quals parameter.
	* decl.c (build_this_parm): New function.
	(grokfndecl): Use it.  Do not pass quals to grokclassfn.
	(grokdeclarator): Rename quals to memfn_quals.  Avoid allocating
	unnecessary TYPE_DECLs.  Correct qualification of member function
	types.  Tidy.
	* method.c (implicitly_declare_fn): Use build_this_parm.
	* friend.c (do_friend): Remove quals parameter.
	* decl2.c (grok_method_quals): Remove.
	(build_memfn_type): New function.
	(build_artificial_parm): Give it external linkage.
	(grokclassfn): Remove quals parameter.  Do not build "this"
	PARM_DECL here.
	PR c++/26912
	* g++.dg/template/friend41.C: New test.

From-SVN: r113213