save only global processes on global zone ps

Save only processes that are running in the global zone on Solaris.
(Minor/pedagogy) This is one of the places where an assignment inside a conditional might be apt.
```
ssize_t res;
while (0 <= (res = CfReadLine(&pbuff, &pbuff_size, psf))) {  Chop(pbuff, pbuff_size); ... }
cf_pclose(psf);
free(pbuff);
if (!feof(psf)) { Log(...); return false; }
return true;
```
which saves duplication of the clean-up code.