Ada: Fix subtype constraint not applied to a view conversion

The view conversion is constrained when its operand object is constrained.

gcc/ada/
	* exp_ch6.adb (Create_Extra_Actuals): Pass True for the extra actual
	of the Constrained attribute when the actual contains a conversion
	to a constrained subtype.
	* sem_res.adb (Resolve_Actuals): Skip the resolution of an actual
	that is a view conversion in fewer cases.  Remove redundant test.