Update test results and a failing test.

Author: tjj2017

testsuite/gnat2goto/tests/separate_subprog/p.adb

@@ -11,5 +11,7 @@ procedure P (X : in out integer) is
    Old_X : constant Integer := X;
 begin
    Inc (X);
+   --  The following assert should succeed if the possibility
+   --  overflow is ignored.
    pragma Assert (X = Old_X + 1);
 end P;

testsuite/gnat2goto/tests/separate_subprog/test.out

@@ -1,3 +1,3 @@
 [2] file p-inc.asu line 6 assertion: SUCCESS
-[1] file p.adb line 14 assertion: FAILURE
+[1] file p.adb line 16 assertion: FAILURE
 VERIFICATION FAILED