ada: Fix endless loop on Address aspect for object with dynamic address

The freezing machinery ends up inserting a freeze node into its own Actions
list, which causes Expand_N_Freeze_Entity to enter an endless loop, because
Remove_Init_Call incorrectly returns the initialization call of a different
variable than the one for which it was invoked.

gcc/ada/ChangeLog:

	* exp_util.adb (Remove_Init_Call.Find_Init_Call_In_List): Check that
	the first actual denotes the expected variable modulo qualification
	and conversion.