If a test appears in 2 ProblemList.txt files and one has platform(s) specified but the other does not (which should be equivalent to `generic-all`), then the test might not be excluded on some platforms.

The reason seems to in `com/sun/javatest/regtest/config/RegressionParameters.java`:

   414 if (platforms.length == 0 || (platforms.length == 1 && platforms[0].length() == 0)) {
   415 return true;
   416 }
   417
   418 for (String p: platforms) {
   419 if (osPlatforms.contains(p.toLowerCase())) {
   420 return true;
   421 }
   422 }

Here, suppose the 2 ProblemList.txt files looks like

```
$ cat p1
path/to/test linux-all

$ cat p2
path/to/test
```

Then `platforms` will be an array `{"", "linux-all"}`. Since `osPlatforms` does not contain an empty string, then the test will not match on a non-linux platform.

We should probably add a `|| p.length() == 0` on line 419, just like what line 415 is doing now.

Workaround: append "generic-all" to p2.