re PR c++/54506 (Defaulted move constructors and move assignment operators are erroneously defined as deleted)

	PR c++/54506
	* decl.c (move_signature_fn_p): Split out from move_fn_p.
	* method.c (process_subob_fn): Use it.
	* cp-tree.h: Declare it.

From-SVN: r191140