On a modern Windows OS, you can rename an in-use file despite not being
able to write to it. With the introduction of the virtual camera, it is
now quite common that users will have in-use files when updating. This
commit renames in-use files, allowing the new version to be installed.
Upon a reboot, the previously in-use file will be deleted.

If an update failed to install, it would leave a single temporary file
behind for that particular patch / file.

With the queued connection in d68484e7, the "Deselect" signal for
sources which are being deleted is never fired, as the object is gone by
the time the queued signal is processed. This results in the context bar
not updating.

This commit adds a new UpdateContextBarDeferred function, allowing
queuing of only the context bar update instead of the whole signal
handler.

VS2019 32bit redist does not have/use vcruntime140_1.dll, so remove
those checks from the installer and auto-updater.

rtmp-services: Update Steam

It's a bit too close to release, so revert #3856 for now until there's
an open PR window instead.

The previous calculation was completely broken, returning offset
timestamps in the best case, and complete insanity in the worst case
(e.g. if an xrun occurs or JACK otherwise has a glitch).

This lock causes a deadlock when freeing the JACK client while a
process callback is pending:

deactivate_jack -> locks mutex
   JACK thread -> calls jack_process_callback
   jack_process_callback -> blocks on mutex
jack_client_close -> joins JACK thread
(deadlock as the process callback never returns)

Instead, just don't lock the mutex. This is only mutexing on
creation/destruction of the JACK client. This is not necessary: the
process callback will only run after jack_activate (which is right
before the mutex is released in jack_init()), and will stop running
by the time jack_client_close returns. We don't actually need to
unregister any ports, so just call jack_client_close first thing in
deactivate_jack, which will guarantee the process callback has
completed before returning.

In fact, jack_process_callback isn't allowed to lock any mutexes or
allocate any memory at all, so this plug-in is still broken in this way
as obs_source_output_audio does that. This can cause audio xruns, as
realtime guarantees are violated. This is something that should be
fixed in the future, but at least it's not a deadlock.

Ports which do not feed audio back into JACK should be marked as terminal.
This allows latency compensation to work properly.

PulseAudio code needs to be called with the PA lock held. This chiefly
fixes multiple races during stream shutdown:

* If the functions are called without the lock held, deferred event
  handling races end up with PA infinite looping on the mainloop, or
  asserting, or other badness, as the reentrant calls cause data
  structure corruption on the PA side.
* If we don't reset our callbacks, PA might call us even after we
  request stream disconnection (since the stream actually getting fully
  shut down is asynchronous), and then we dereference NULL pointers from
  our userdata etc. PA will keep its data structures alive until necessary
  via reference counting, but not ours.

The lock around pa_stream_begin_write doesn't result from any issues I
experienced, but it looks correct; PA doesn't say anywhere that that
function is thread-safe.

If the user hasn't specifically set a rate control and left OBS at the
default of CBR, the settings loaded by GetDataFromJsonFile will not have
a rate_control parameter present. This causes the replay buffer to think
the user is in VBR mode and use the wrong settings for determining
maximum buffer size. Fixes #2516.

The (de)select signal can come from a obs_scene_enum_items
which locks the scene. The Qt::QueuedConnection makes sure
the (de)select is handled outside of that lock.
Fixes the deadlock from #3673

CI: Update macOS to Qt 5.15.2 and deps 2020-12-11

Regression introduced by dc4e2050: while the stop detection is pending,
it should still return false so the rest of the discard code can run.
Otherwise, the source audio will remain in the buffer, lagging the
source and triggering audio buffering increases until max audio
buffering is reached.

Use json11 instead.

Steam now automatically selects the closest available server

Replace it with the typical strerror for platforms that dont have full
posix support (freebsd/clang).

fixes #3835

When /bin/sh isn't bash, the previous line always appears to succeed,
and modinfo's output is not redirected, because it actually runs
modinfo in the background (which always succeeds) then opens and closes
/dev/null without doing anything to it. This causes us to always think
that the v4l2loopback module is installed, even when it isn't.

Fixes an issue where the hotkey entries would be duplicated
(including in the UI hotkey list) on every Profile switch.

This matches the behaviour of Scenes and the Audio Mixer.

Gives the MachServer a unique name which was forgotten in a previous commit

The vod track in advanced output mode would be overwritten by twitch
soundtrack's vod track. Additionally, simple output mode would overwrite
twitch's soundtrack vod track even when vod track was turned off in
settings.

So instead, if vod track is off, don't clear the secondary encoder
unless it's explicitly our encoder. Additionally, make sure that
advanced output mode's vod track encoder behaves consistently with
simple output mode's vod track so it doesn't get overwritten.

Was meant to be "adv" meaning advanced rather than "avc"

Similar to 315fbd6f and 6071098a, ignore non-fatal errors during the
remux process. It's possible OBS itself writes a file that generates
these errors when remuxed.

Previously sliders would not be disabled when the the obs_property was
disabled.

UI: fix typo