Software backend: Delete forked PixelEngine.

Mostly just zapping a bunch of duplicated code; the only interesting thing
going on here is the changes to the performance counter implementation.
SWBackend: Fix code style.
Merge pull request #224 from magumagu/swrender-deletepixelfork

Software backend: Delete forked PixelEngine.
D3DBackend: Don't recompute ID3D11Layout.

CreateInputLayout requires a shader as an input, but it only cares about
the signature; we don't need to recompute it for different shaders with
the same inputs.
Merge pull request #223 from magumagu/d3d-cache-input-layout

D3DBackend: Don't recompute ID3D11InputLayout for different shaders.
CPUDetect: add support for MOVBE detection
x64Emitter: Add the MOVBE instruction.
Jit_Util: Provide two util functions to load/store and swap values, using MOVBE internally when possible.
JitAsmCommon: Use MOVBE everywhere it matters (!x86 only code, !old CPU support code).
Jit64: Use LoadAndSwap/SwapAndStore where it makes sense.
Merge pull request #173 from delroth/movbe

Optimize memory access on Haswell by using MOVBE when possible.
VideoBackend: remove unused config vars.

No point to keeping around variables which are always "true".
Merge pull request #235 from magumagu/videobackend-unused-config

VideoBackend: Remove unused config variables.
OpenGL config: clear backend_info.Adapters on init

Fixes a minor UI glitch where if you switch from Direct3D to OpenGL, the
OpenGL config page would appear to have an adapter choice available.
Merge pull request #264 from magumagu/opengl-clear-adapters

OpenGL: Clear backend_info.Adapters on initialization
VideoBackends: Use unordered map for shader objects