PR c++/19203, implement DR 214

PR c++/19203, implement DR 214

cp:
	PR c++/19203, implement DR 214
	* call.c (joust): Use more_specialized_fn.
	* cp-tree.h (DEDUCE_ORDER): Remove.
	(more_specialized): Replace with ...
	(more_specialized_fn): ... this.
	* pt.c (maybe_adjust_types_for_deduction): Remove DEDUCE_ORDER
	case.
	(type_unification_real): Remove DEDUCE_ORDER case.
	(more_specialized): Replace with ...
	(more_specialized_fn): ... this.  Implement DR 214.
	(most_specialized_instantiation): Use get_bindings_real directly.
testsuite:
	PR c++/19203, DR 214
	* g++.dg/parse/ambig3.C: Not ambiguous.
	* g++.dg/template/spec20.C: New.
	* g++.dg/template/spec21.C: New.

From-SVN: r97336