Fix handling of test failures due to uncaught exceptions

We don't just want to exit here, but `longjmp()` back to the conditional
via a call to `DeepState_Fail()`. In doing so, we end up in the common
`DeepState_CatchFail()` branch, which exits with the same nonzero error
code, but also saves the test case if appropriate.

src/include/deepstate/DeepState.h

@@ -423,7 +423,7 @@ static void DeepState_RunTest(struct DeepState_TestInfo *test) {
 
 #if defined(__cplusplus) && defined(__cpp_exceptions)
     } catch(...) {
-      exit(1);
+      DeepState_Fail();
     }
 #endif  /* __cplusplus */