Added GetAudioRendererSampleRate, GetAudioRendererSampleCount & GetAudioRendererMixBufferCount

 hid: Stub DisconnectNpad() 

externals: Update to SDL2-2.0.8.

GL renderer: Pick the streambuffer from citra and use them.

Don't emut copies, especially not for data, which is used once. They just end in a huge GPU overhead.

Please see https://github.com/citra-emu/citra/pull/3666 for more details.

Prevents clang-format from butchering them.

This is required by ARMS.

gl_shader_decompiler: Fix SetOutputAttributeToRegister empty check.

 CMakeLists: Change MSVC14 variable to MSVC_VERSION

GetAudioRendererSampleRate is set as a "STUB" as a game could check if the sample rate it sent and the sample rate it wants don't match. Just a thought of something which could happen so keeping it as stub for the mean time

Stub UpdateUserPresence

gl_shader_decompiler: Fix GLSL compiler error with KIL instruction.

Needed for Retro City Rampage to go in game

Several Friend service fixes

core: Namespace EmuWindow

gl_rasterizer: Silence implicit truncation warning in SetupShaders()

GPU/Maxwell3D: Implemented an alternative set of blend factors.

RasterizerGL: Ignore invalid/unset vertex attributes.

These are used by nouveau and some games like SMO.

- Used by Go Vacation

This should make the es2gears example not crash anymore.

- Used by Splatoon 2.

Previously this would warn of truncating a std::size_t to a u32. This is
safe because we'll obviously never have more than UINT32_MAX amount of
uniform buffers.

Gets the class out of the global namespace.

gl_shader_decompiler: Improve handling of unknown input/output attributes.

Implement render target formats RGBA8_SNORM and RG8_SNORM.

The rest of the CMake script uses lowercase for commands (which is the
general CMake style), making it more consistent with surrounding code.

Use of the MSVC14 variable is discouraged in the CMake documentation
(which makes sense, since MSVC_VERSION is the more general appliable
variable).