This means it now works with any CMake released since 2014 instead of 2018.
This was mostly just readding some special cases, and requiring 3.11.0 only
for Windows Stores apps, which isn't unreasonable. The biggest concern is
a Linux distribution not having a recent CMake; most other places will be
manually downloading and installing their own CMake.
Fixes#4930.
The joystick subsystem has complex precedence logic to deal multiple competing
backends like XInput, RawInput, and WGI. Let it fire the MaybeAdd callbacks
for joystick devices, since it knows which backend will end up managing them.
This resolves a situation where the RawInput joystick backend would take
control of an XInput device but the XInput haptic backend would still create
a haptic device. Since the XInput joystick backend didn't own the underlying
joystick device, we'd end up with an orphaned haptic device that didn't work
with SDL_HapticOpenFromJoystick() on the associated joystick device.
A racing reader could read from our fd between SDL_IOReady()/X11_Pending()
and our call to XNextEvent() which will cause XNextEvent() to block for
more data. Avoid this by using XCheckIfEvent() which will never block.
This also fixes a bug where we could poll() for data, even when events were
already read and pending in the queue. Unlike the Wayland implementation,
this isn't totally thread-safe because nothing prevents a racing reader
from reading events into the queue between our XCheckIfEvent() and
SDL_IOReady() calls, but I think this is the best we can do with Xlib.
This API and implementation comes from the Unreal Engine branch of SDL, which
originally called this "SDL_ConfineCursor".
Some minor cleanup and changes for consistency with the rest of SDL_video, but
there are two major changes:
1. The coordinate system has been changed so that `rect` is _window_ relative
and not _screen_ relative, making it easier to implement without having
global access to the display.
2. The UE version unset all rects when passing `NULL` as a parameter for
`window`, this has been removed as it was an unused feature anyhow.
Currently this is only implemented for X, but can be supported on Wayland and
Windows at minimum too.