Making the non-executable ACATS tests executable

The Ada Conformity Assessment Test Suite (ACATS) includes both positive and negative tests. The negative tests have intentional errors that a compiler is intended to diagnose with a compile-time error message. Interestingly, the negative tests also include numerous "OK" lines that the compiler must not reject. But the absence of an error message on the "OK" lines is not always a convincing demonstration that the "OK" lines were correctly compiled, since the negative tests are not executable. By removing the intentional errors from a copy of each negative test, we are able to compile and run the resulting modified tests, demonstrating more convincingly that the "OK" lines are correctly compiled.