[Ada] Use correct subtype for call to Last in formal vectors

2019-12-12  Claire Dross  <dross@adacore.com>

gcc/ada/

	* libgnat/a-cofove.adb, libgnat/a-cfinve.adb (Find_Index): Use
	Extended_Index for call to Last.

From-SVN: r279284

gcc/ada/ChangeLog

+2019-12-12  Claire Dross  <dross@adacore.com>
+
+	* libgnat/a-cofove.adb, libgnat/a-cfinve.adb (Find_Index): Use
+	Extended_Index for call to Last.
+
 2019-12-12  Gary Dismukes  <dismukes@adacore.com>
 
 	* sem_ch3.adb, sem_util.adb: Minor reformatting.

gcc/ada/libgnat/a-cfinve.adb

@@ -458,7 +458,7 @@ is
       Index     : Index_Type := Index_Type'First) return Extended_Index
    is
       K    : Count_Type;
-      Last : constant Index_Type := Last_Index (Container);
+      Last : constant Extended_Index := Last_Index (Container);
 
    begin
       K := Capacity_Range (Int (Index) - Int (No_Index));

gcc/ada/libgnat/a-cofove.adb

@@ -379,7 +379,7 @@ is
       Index     : Index_Type := Index_Type'First) return Extended_Index
    is
       K    : Count_Type;
-      Last : constant Index_Type := Last_Index (Container);
+      Last : constant Extended_Index := Last_Index (Container);
 
    begin
       K := Capacity_Range (Int (Index) - Int (No_Index));