Update xserver-xorg-video-intel to 2.21.11^w.12^w.13

We're holding off on 2.21.11 because there were so many fixes for that release right after it released, 2.21.12 should be out any day now and will go in

Indeed, I'm just waiting for the US to wake up after its long weekend and see if there were any more issues with the new features in 2.21.11.

2.21.13 released few days ago
Official Announcement http://www.spinics.net/lists/xorg/msg55592.html

Highlights of Intel X.Org Driver 2.21.13:

• A potential memory corruption has been fixed;
• A performance regression on Ironlake, which occurred due to inadvertently flushing after every operation, has been fixed;
• /proc/cpuinfo is now used if cpuid4 is not available;
• A conflict that occurred when probing the initial KMS configuration for ZaphodHeads has been fixed;
• Rendering to Y-tiled surfaces is now permitted;
• A pixmap is now created in ordinary system memory for depth=1 uploads.

This bug was fixed in the package xserver-xorg-video-intel - 2:2.21.12-1ubuntu1

---------------
xserver-xorg-video-intel (2:2.21.12-1ubuntu1) saucy; urgency=low

  [ Maarten Lankhorst ]
  * Merge from unreleased debian git (LP: #1198409, #1173557, #1199746, #1200766)
    Remaining changes:
    - Use SNA by default.

  [ Robert Hooker ]
  * Cherry-pick 3 commits from upstream git to fix SNA regressions in 2.21.12
    (34c9b759f, 7f76a2bf3, a764a6e69b)

  [ Christopher James Halse Rogers ]
  * Add initial XMir support patch
 -- Christopher James Halse Rogers <email address hidden> Thu, 01 Aug 2013 16:06:42 +1000

Few days ago 2.21.14 version released

Changelog:

· Initial performance tuning for HSW:GT3e
· Fix a crash with Planetary Annihilation
· Disable triple buffering for compositors
· Reserve space in the exec buffer array for deferred VBOs. https://bugs.freedesktop.org/show_bug.cgi?id=67504

http://cgit.freedesktop.org/xorg/driver/xf86-video-intel/commit/?id=0cd154039ab02799dc972d93c415e762226df1aa

Changelog

+Release 2.21.15 (2013-08-21)
+============================
+Some build fixes for the BSDs and alternate compiler, and conflicting
+configure options and a critcial fix for some PRIME setups.
+
+ * Don't fail to configure if DRI1 is not available and the user asks
+ for both DRI and KMS-only
+ [Regression from 2.21.14]
+
+ * Lots of miscellaneous fixes for older gcc, other compilers and BSD.
+
+ * Initial framework support for hosted X.
+
+ * Improve transition from fbcon to X with multiple outputs and extended
+ desktops.
+
+ * Ensure the framebuffer exists before checking it against the CRTC
+ constraints.
+ https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/121234
+ [Regression from 2.21.10]
+
+ * Add RGB overlay support for Ironlake and later.
+
+ * Don't release the overlay buffer too early, i.e. before the client
+ disables the Xv image.
+
+ * Tweak the ring switching logic to reduce use of semaphores on
+ Sandybridge and later - a delicate balancing act between trying to
+ use the faster engine for the task and preventing concurrent use of
+ multiple rings.