c++: squash cp_build_qualified_type/_real

This combines the two differently named versions of the same function
into a single function utilizing a default argument.

gcc/cp/ChangeLog:

	* cp-tree.h (cp_build_qualified_type_real): Rename to ...
	(cp_build_qualified_type): ... this.  Give its last parameter
	a default argument.  Remove macro of the same name.
	* decl.cc (grokdeclarator): Adjust accordingly.
	* pt.cc (tsubst_aggr_type): Likewise.
	(rebuild_function_or_method_type): Likewise.
	(tsubst): Likewise.
	(maybe_dependent_member_ref): Likewise.
	(unify): Likewise.
	* tree.cc (cp_build_qualified_type_real): Rename to ...
	(cp_build_qualified_type): ... this.  Adjust accordingly.