tests: Return EXIT_FAILURE/EXIT_SUCCESS instead of -1/0

When using VIR_TEST_MAIN() or VIR_TEST_MAIN_PRELOAD() macros, the
retval of mymain() will become retval of main(). Hence, mymain()
should use EXIT_FAILURE and EXIT_SUCCESS return values for
greater portability. Another reason is that otherwise our summary
printing of failed tests doesn't work (see following commit for
more info).

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

tests/scsihosttest.c

@@ -282,7 +282,7 @@ mymain(void)
     VIR_FREE(fakerootdir);
     VIR_FREE(fakesysfsdir);
     VIR_FREE(scsihost_class_path);
-    return ret;
+    return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 }
 
 VIR_TEST_MAIN(mymain)