pa.md (decrement_and_branch_until_zero): Use `Q' constraint instead of `m' constraint.

	* config/pa/pa.md (decrement_and_branch_until_zero): Use `Q' constraint
	instead of `m' constraint.  Likewise for unnamed movb comparison
	patterns using reg_before_reload_operand predicate.
	* config/pa/predicates.md (reg_before_reload_operand): Tighten
	predicate to reject register index and LO_SUM DLT memory forms
	after reload.

From-SVN: r219162