ada: Add Check_Error_Detected before "raise Bad_Attribute"

ada: Add Check_Error_Detected before "raise Bad_Attribute"

We shouldn't raise Bad_Attribute if there is no error.
This patch adds a call to Check_Error_Detected to make sure that's true.
(There are other cases where we raise Bad_Attribute;
this patch doesn't try to fix them all.)

gcc/ada/

	* sem_attr.adb
	(Analyze_Attribute): Add a call to Check_Error_Detected.