[Ada] Remove return statements after procedure calls that don't return

A new warning about unreachable code that follows calls to procedures
with No_Return would flag many unnecessary return statements. Those
returns statements were applied inconsistently, so this patch is
actually more a style cleanup.

gcc/ada/

	* sem_attr.adb, sem_prag.adb: Remove dead return statements
	after calls to Error_Attr, Error_Pragma, Error_Pragma_Arg and
	Placement_Error. All these calls raise exceptions that are
	handled to gently recover from errors.
2 files changed