Added test-case for a subtraction bug.

Rev: src/testsuite.in:1.121

src/testsuite.in

-stest_true([["$Id: testsuite.in,v 1.120 1998/08/10 23:33:30 hubbe Exp $"]])
+stest_true([["$Id: testsuite.in,v 1.121 1998/09/01 16:57:46 grubba Exp $"]])
 cond([[all_constants()->_verify_internals]],
 [[
   test_do(_verify_internals())
@@ -11,6 +11,7 @@ test_eq(1e-1,0.1)
 test_eq('\x20',32)
 test_eq("\x20","\040")
 test_eq('Å',"Å"[0])
+test_eq(0x80000000-0x80000000, 0)
 test_true([[1.0e-40]])
 test_eq([[#"foo
 bar"]],[["foo\nbar"]])