D3D: Use floating points for viewport parameters.

OpenGL 4.1 allows for a similar change thanks to ARB_viewport_array, but we don't make use of this, yet.
[Android] Fix PCH build. Clean up DolphinWX cmake file a little bit. Modify our android cmake toolchain file to make the default build location not be source root, because that is stupid.
Fix FXAA shader for OpenGL ES 3.
OGL: Use floating points for viewport parameters.

As told by neobain, ARB_viewport_array introduced float viewports.
They must be supported on OGL4.1+, but it's usually also implemented on 3.3 GPUs.
[viewport-float] Fix OpenGL ES 3 build.
VideoCommon: Drop D3D9 SSAA implementation

This isn't needed for both OGL+D3D11 as they support sample shading directly. So we
could use the common MSAA util shaders instead of writing custom ones.
Merge branch 'viewport_float'
VideoCommon: move ViewportCorrection into VideoCommon

D3D doesn't allow bigger viewports than rendertargets. But flipper does, so the viewport will be clipped and the transformation matrix will be changed.
This was done in the D3D backend itself. This is now moved into VideoCommon. This don't reduce code, but in this way, VideoCommon doesn't depend on the backends.
ogl: don't call SetViewportChanged from backend as it's not needed any more
d3d: use backend based UpdateViewport instead of VideoCommon one
ogl: remove some unneeded includes
VideoCommon: remove constants.depthparams[2+3] as they aren't used in the shader at all
VideoCommon: drop UpdateViewportWithCorrection

It's only used once in BPFunction which itself is also only used once.
So the setter is moved to BPStructs like all other ones.
ogl: don't force depth+stencil for default framebuffer
ogl: ceil viewport, rounding isn't supported on vs and this is more like the old behavior
Merge branch 'viewportCorrection'