ada: Fix expansion of protected subprogram bodies

ada: Fix expansion of protected subprogram bodies

System.Tasking.Protected_Objects.Lock can raise exceptions, but that
wasn't taken into account by the expansion of protected subprogram
bodies before this patch. More precisely, there were cases where
calls to System.Tasking.Initialization.Abort_Undefer were
incorrectly omitted. This patch fixes this.

gcc/ada/

	* exp_ch7.adb (Build_Cleanup_Statements): Adapt to changes
	made to Build_Protected_Subprogram_Call_Cleanup.
	* exp_ch9.adb (Make_Unlock_Statement, Wrap_Unprotected_Call):
	New functions.
	(Build_Protected_Subprogram_Body): Fix resource management in
	generated code.
	(Build_Protected_Subprogram_Call_Cleanup): Make use of newly
	introduced Make_Unlock_Statement.