* Joystick hotplug support (#4141)

* use SDL_PollEvent instead of SDL_JoystickUpdate

Register hot plugged controller by GUID if they were configured in a previous session

* Move SDL_PollEvent into its own thread

* Don't store SDLJoystick pointer in Input Device; Get pointer on each GetStatus call

* Fix that joystick_list gets cleared after SDL_Quit

* Add VirtualJoystick for InputDevices thats never nullptr

* fixup! Add VirtualJoystick for InputDevices thats never nullptr

* fixup! fixup! Add VirtualJoystick for InputDevices thats never nullptr

* Remove SDL_GameController, make SDL_Joystick* unique_ptr

* fixup! Remove SDL_GameController, make SDL_Joystick* unique_ptr

* Adressed feedback; fixed handling of same guid reconnects

* fixup! Adressed feedback; fixed handling of same guid reconnects

* merge the two joystick_lists into one

* make SDLJoystick a member of VirtualJoystick

* fixup! make SDLJoystick a member of VirtualJoystick

* fixup! make SDLJoystick a member of VirtualJoystick

* fixup! fixup! make SDLJoystick a member of VirtualJoystick

* SDLJoystick: Addressed review comments

* Address one missed review comment

Inline the WriteReg helper as it is called ~20k times per frame.

This moves the hot loop into video_core. This refactoring shall reduce the CPU overhead of calling ProcessCommandList.

This virtual function is called in a very hot spot, and it does nothing.

If this kind of feature is required, please be more specific and add callbacks
in the switch statement within Maxwell3D::WriteReg. There is no point in having
another switch statement within the rasterizer.

- Fixes an issue with Octopath Traveler leaving stale data here.

- Several misc. changes to ConfigureFramebuffers in support of this.

- Used by Octopath Traveler (with multiple render targets).

With the named port functionality all migrated over to the kernel,
there's no need to keep this around anymore.

The compatibility list isn't modified within any of the slots connected
to this signal, so we can make it const to enforce immutability.

Lets us keep the generic portions of the compatibility list code
together, and allows us to introduce a type alias that makes it so we
don't need to type out a very long type declaration anymore, making the
immediate readability of some code better.

- Fixed all warnings, for renderer_opengl items, which were indicating a
possible incorrect behavior from integral promotion rules and types
larger than those in which arithmetic is typically performed.
- Added const for variables where possible and meaningful.
- Added constexpr where possible.

When not set, this tells the GPU to only use the X size when performing a DMA copy.
This is only implemented for linear->linear and tiled->tiled copies. Conversion copies still retain the assert.

This bit is unset by some games for various purposes, and by nouveau when copying the vertex buffers.

Previously the version number got hidden after starting a game.

This hopefully helps our cache not to redundant upload the vertex buffer.

# Conflicts:
#	src/video_core/renderer_opengl/gl_rasterizer.cpp

* video_core: Arithmetic overflow fix for gl_rasterizer

- Fixed warnings, which were indicating incorrect behavior from integral
promotion rules and types larger than those in which arithmetic is
typically performed.

- Added const for variables where possible and meaningful.

* Changed the casts from C to C++ style

Changed the C-style casts to C++ casts as proposed.
Took also care about signed / unsigned behaviour.

- Will not work for non-2d textures, and was not used anyways.

This has gotten sufficiently large enough to warrant moving it to its
own source files. Especially given it dumps the file_sys headers around
code that doesn't use it for the most part.

This'll also make it easier to introduce a type alias for the
compatibility list, so a large unordered_map type declaration doesn't
need to be specified all the time (we don't want to propagate the
game_list_p.h include via the main game_list.h header).

Given we now have the kernel as a class, it doesn't make sense to keep
the current process pointer within the System class, as processes are
related to the kernel.

This also gets rid of a subtle case where memory wouldn't be freed on
core shutdown, as the current_process pointer would never be reset,
causing the pointed to contents to continue to live.