Fix QSettings autotest for VxWorks

No users/groups on VxWorks.

Change-Id: I88912c93fa59dc7c00bdbb973fc34ecd631b3316
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>

tests/auto/corelib/io/qsettings/tst_qsettings.cpp

@@ -694,7 +694,9 @@ void tst_QSettings::testErrorHandling()
 #ifdef Q_OS_WIN
     QSKIP("Windows doesn't support most file modes, including read-only directories, so this test is moot.");
 #elif defined(Q_OS_UNIX)
+#if !defined(Q_OS_VXWORKS)  // VxWorks does not have users/groups
     if (::getuid() == 0)
+#endif
         QSKIP("Running this test as root doesn't work, since file perms do not bother him");
 #else
     QFETCH(int, filePerms);