AVFoundation: fix build with iOS 8.0 SDK.

Change-Id: I9d9b97ad88631ba12a289f7575ca53386e592bd1
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
WMF: Fix null ptr derefernce in MFPlayerSession.

Checking the sender of the mediaSourceReady signal to prevent accessing
the incorrect source resolver.

When the source resolver has finished the asynchronous operation and
the source resolver gets recreated in the player at the same time in a
different thread the signal mediaSourceReady still gets emitted from the
old source resolver.

The player assumes that the signal was emitted from the current source
resolver and accesses the unresolved media source in the
handleMediaSourceReady slot.

Task-number: QTBUG-39980
Change-Id: Ic52f6918995aac250048d91f89c520cfea111bd0
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>
WMF: Use media source only when it is initialized.

Change-Id: I0efcf6139d0b81194cf25383025f080f8656728c
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>
QNX: Fix resetting video surface

If video surface object is set to 0, it must not be accessed to set a
property on it.

Task-number: QTBUG-40746
Change-Id: I1de0e5495918d3ea06706412fab15bf1af012f36
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Merge remote-tracking branch 'origin/5.3' into 5.4

Change-Id: I716fd3acb69e424047691069cd4a781f656d0487