Add explicit O- option in tests needing it

git-svn-id: trunk@20597 -

tests/test/cg/tcnvint5.pp

@@ -1,3 +1,7 @@
+
+{ This test requires overflow check to be off }
+{$O-}
+
 var
   error: boolean;
 

tests/test/cg/tcnvint6.pp

@@ -1,4 +1,7 @@
 
+{ This test requires overflow check to be off }
+{$O-}
+
 procedure error(n: longint);
 begin
   writeln('Test failed: ', n);