tests: skip setPermissions test if running as root

Running this test as root doesn't make sense, and it is the reason
why QNX is failing.

Pick-to: 6.6 6.5
Change-Id: Ibbdce9090882cb9dd87d7fcd0802a481f9e7883c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

tests/auto/corelib/io/qfile/tst_qfile.cpp

@@ -1464,8 +1464,9 @@ void tst_QFile::setPermissions_data()
 
 void tst_QFile::setPermissions()
 {
-#ifdef Q_OS_QNX
-    QSKIP("This test doesn't pass on QNX and no one has cared to investigate.");
+#ifdef Q_OS_UNIX
+    if (::getuid() == 0)
+        QSKIP("Running this test as root doesn't make sense");
 #endif
     QFETCH(bool, opened);