Update changelog for 5.2.1

Change-Id: Id1df662afb2ec0e7eb7055bbc2c5c523a5bda125
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>
Fixes mediaplayer crashes on OSX

Fixes the "libqavfmediaplayer.dylib 0x0000000110fa7c8c -[AVFMediaPlayerSessionObserver unloadMedia]" crash on Macs.
The problem was: writing to memory that had already been released. If not sure, one should always check if the objects exist before deleting it.

Solution tested on OSX 10.7, 10.8, 10.9

[ChangeLog][qtmultimedia][avfmediaplayersession]

Task-number: QTBUG-34213
Change-Id: Iac108711851c348e96e73542b4e71653007eeb54
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
Fix sending End Of Stream on gst plugin

When streaming to gst a typefind operation
is performed which jumps around to find which
codec the file provides, this fix the call to
send an EOS before we try to read and not after
which causes confusion to gst.

Task-number: QTBUG-32963
Change-Id: I2658b6a4e960430c8ab422a3bee5e11956663116
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>
Merge remote-tracking branch 'origin/release' into stable

Change-Id: If97b68b56071e241c659ddd231f28e433954d7be