Fixed compile error on Mac OS X Lion, missing include statement.

Also, don't try and build the quicktime/CG bits on QPA for now,
since that really doesn't seem to work.

Change-Id: If88b94bae3c092f2480318fa169250c03de44784
Reviewed-on: http://codereview.qt.nokia.com/2545
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

src/plugins/plugins.pro

@@ -41,5 +41,6 @@ unix:!mac {
 }
 
 mac:!simulator {
-    SUBDIRS += audiocapture qt7
+    SUBDIRS += audiocapture
+    !qpa: SUBDIRS += qt7
 }