Don't run the Linux configure tests on OS X

This can create weird senarios where they pass due to MacPorts actually
having the dependencies.  We don't support this, so dont allow it to
happen.

Task-number: QTBUG-27352
Change-Id: I2be104549b5d1e9a61a734d05b3c21afcd2f6828
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: Caroline Chao <caroline.chao@digia.com>

qtmultimedia.pro

@@ -6,6 +6,8 @@ win32 {
     qtCompileTest(wmp)
     qtCompileTest(wmf)
     qtCompileTest(evr)
+} else:mac {
+    qtCompileTest(avfoundation)
 } else {
     qtCompileTest(alsa)
     qtCompileTest(pulseaudio)
@@ -18,9 +20,5 @@ win32 {
     qtCompileTest(xvideo)
 }
 
-mac {
-    qtCompileTest(avfoundation)
-}
-
 load(qt_parts)