Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

We haven't updated the default post-build copy paths yet, as the new
local directory is not yet well-supported by DAWs.

With this patch applied, the DemoRunner should build under MinGW, and be
(nearly) feature-complete compared to the MSVC build.

Specifically, when building with MinGW:
- Adds support for accessibility
- Fixes build issues in the juce_video module
- Fixes a link issue in the VST3 wrapper when VST3_CAN_REPLACE_VST2 is
  defined
- Adds support for the new-style native FileChooser
- Tidies up some other low-severity warnings

Known issues:
- Direct2D rendering is still not supported when building with MinGW due
  to ABI compatibilities.

The Apple threading documentation [^1] says the following:

> The second argument to pthread_setschedparam is the desired policy,
  which can currently be one of SCHED_FIFO (first in, first out),
  SCHED_RR (round-robin), or SCHED_OTHER. The SCHED_OTHER policy is
  generally used for extra policies that are specific to a given
  operating system, and should thus be avoided when writing portable
  code.

This appears to differ from the policy semantics on Linux and BSD, where
FIFO and RR are both explicitly real-time policies.

Therefore, on Linux/BSD we only enable the RR policy if the requested
priority is 8 or higher. Meanwhile, on macOS, we map all thread
priorities (0 - 10) onto the RR policy with an appropriate priority.

[^1]: https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/scheduler/scheduler.html

The Apple threading documentation [^1] says the following:

> The second argument to pthread_setschedparam is the desired policy,
  which can currently be one of SCHED_FIFO (first in, first out),
  SCHED_RR (round-robin), or SCHED_OTHER. The SCHED_OTHER policy is
  generally used for extra policies that are specific to a given
  operating system, and should thus be avoided when writing portable
  code.

This appears to differ from the policy semantics on Linux and BSD, where
FIFO and RR are both explicitly real-time policies.

Therefore, on Linux/BSD we only enable the RR policy if the requested
priority is 8 or higher. Meanwhile, on macOS, we map all thread
priorities (0 - 10) onto the RR policy with an appropriate priority.

[^1]: https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/scheduler/scheduler.html

Clang versions 5 to 8 inclusive seem to struggle to compile JUCE when
JUCE_BEGIN_NO_SANITIZE is used. This is unexpected, as simpler programs
using the same macro definitions compile correctly on clang 5.