Actually, two enum classes, since for some reason there are two separate
yet identical `PollFD` types used in the codebase.  I get that one is
ABI-compatible with the Switch while the other is an abstract type used
for the host, but why not use `WSAPOLLFD` directly for the latter?

Anyway, why make this change?  Because on Apple platforms, `POLL_IN`,
`POLL_OUT`, etc. (with an underscore) are defined as macros in
<sys/signal.h>.  (This is inherited from FreeBSD.)  So defining
a variable with the same name causes a compile error.

I could just rename the variables, but while I was at it I thought I
might as well switch to an enum for stronger typing.

Also, change the type used for values copied directly to/from the
`events` and `revents` fields of the host *native*
`pollfd`/`WSASPOLLFD`, from `u32` to `short`, as `short` is the correct
canonical type on both Unix and Windows.

Fix "explicitly defaulted but implicitly deleted" warning

`PhysicalCore`'s move assignment operator was declared as `= default`,
but was implicitly deleted because `PhysicalCore` has fields
of reference type.  Switch to explicitly deleting it to avoid a Clang
warning.

The move *constructor* is still defaulted, and is required to exist due
to the use of `std::vector<PhysicalCore>`.

video_core: Adjust `NUM` macro to avoid Clang warning

The previous definition was:

    #define NUM(field_name) (sizeof(Maxwell3D::Regs::field_name) / sizeof(u32))

In cases where `field_name` happens to refer to an array, Clang thinks
`sizeof(an array value) / sizeof(a type)` is an instance of the idiom
where `sizeof` is used to compute an array length.  So it thinks the
type in the denominator ought to be the array element type, and warns if
it isn't, assuming this is a mistake.

In reality, `NUM` is not used to get array lengths at all, so there is no
mistake.  Silence the warning by applying Clang's suggested workaround
of parenthesizing the denominator.

yuzu_cmd: Remove 'users_size'

maxwell_dma: Rename RenderEnable::Mode::FALSE and TRUE to avoid name conflict

Port citra-emu/citra#5577: "Update cubeb and request a persistent stream session"

xbyak_abi: Avoid implicit sign conversions

game_list_p: Resolve deprecated usage of QVariant operator<

On Apple platforms, FALSE and TRUE are defined as macros by
<mach/boolean.h>, which is included by various system headers.

Note that there appear to be no actual users of the names to fix up.

Specifically:

    const auto size = sdl2_config->GetInteger("System", "users_size", 0);

The variable is never used, producing a warning.  I wondered if this
ought to be assigning something to in `Settings`, but nothing else in
the codebase ever mentions a setting called "users_size", so I guess
it's safe to remove...

This is designated as obsolete in Qt's docs (see:
https://doc.qt.io/qt-5/qvariant-obsolete.html#operator-lt)

video_core: Resolve more variable shadowing scenarios pt.2

Migrates the video core code closer to enabling variable shadowing
warnings as errors.

This primarily sorts out shadowing occurrences within the Vulkan code.

video_core: Resolve more variable shadowing scenarios

Port citra-emu/citra#5617: "Fix telemetry-related exit crash from use-after-free"

Makes for less reading.

system_version: Update to 11.0.0

Co-Authored-By: xperia64 <xperia64@users.noreply.github.com>

codec: Remove deprecated usage of AVCodecContext::refcounted_frames

This was only necessary for use with the
avcodec_decode_video2/avcoded_decode_audio4 APIs which are also
deprecated.

Given we use avcodec_send_packet/avcodec_receive_frame, this isn't
necessary, this is even indicated directly within the FFmpeg API changes
document here on 2017-09-26:

https://github.com/FFmpeg/FFmpeg/blob/master/doc/APIchanges#L410

This prevents our code from breaking whenever we update to a newer
version of FFmpeg in the future if they ever decide to fully remove this
API member.

Resolves variable shadowing scenarios up to the end of the OpenGL code
to make it nicer to review. The rest will be resolved in a following
commit.

node: Eliminate variable shadowing

vp9/vic: Resolve pessimizing moves

Kernel: Refactor to use 4-instances of Dynarmic & various cleanups and improvements

Prevents logic bugs from accidentally ignoring the return value.

mouse_input/mouse_poller: Minor cleanup

Removes the usage of moves that don't result in behavior different from
a copy, or otherwise would prevent copy elision from occurring.

Allows the struct to be constructed in place.

Removes the use of two static casts and improves the readability of some
vectors slightly.

audio_core: Make shadowing and unused parameters errors

Moves the audio code closer to enabling warnings as errors in general.