Update to the latest Snappy 1.1.2.

Not clear if there are any bugfixes, but there are minor performance
improvements.
Cast away some warnings in Snappy.
Merge pull request #6580 from unknownbrackets/snappy-up

Update Snappy to 1.1.2
Update Android  Readme.txt
Merge pull request #6581 from sum2012/patch-2

Update Android  Readme.txt
X64emitter: merge from dolphin
Add option to use the Android hardware scaler by setting a low resolution
Add an "Auto" mode that makes display res match internal res.

Change wording according to unknown's idea
Merge pull request #6576 from hrydgard/android-hwscaler

Add option to use the Android hardware scaler by setting a low resolution
Update native with ui fix.

Fixes #6584.
Introduce a memory shutdown lock.

This allows the debugger to access memory in a safe way that should never
crash.
Merge pull request #6586 from unknownbrackets/debugger

Introduce a memory shutdown lock
Hide "immersive mode" on pre-kitkat Android.
Make the axis->button mapping code make more sense
De-duplicate updates to axis mapped keys.

Improves mapping an analog stick to the same thing as a dpad, as this reduces
spurious button resets caused by analog stick noise.
Merge branch 'master' of http://github.com/hrydgard/ppsspp into test