c++: templatey type creation

c++:  templatey type creation

This patch makes a couple of type-creation routines available to
modules.  That needs to create unbound template parms, and canonical
template parms.

	gcc/cp/
	* cp-tree.h (make_unbound_class_template_raw): Declare.
	(canonical_type_parameter): Declare.
	* decl.c (make_unbound_class_template_raw): Break out of ...
	(make_unboud_class_template): ... here.  Call it.
	* pt.c (canonical_type_parameter): Externalize.  Refactor & set
	structural_equality for type parms.