Add mono_threads_core_set_name() on Mac.
Merge pull request #973 from methane/fix-build-on-mac

Add mono_threads_core_set_name() on Mac.
Fix monotouch's repl support to build Mono.CSharp (and its dependencies) as well.
[corlib] Filter out any right-to-left sign characters. Fixes #18522
[corlib] Make invariant NumberFormatter thread static too as it has internal static state. Fixes #18599
[corlib] Update test with failure info
[corlib] Fixes CancellationTokenSource dispose race
[runtime] Fix a crash if the thread name is set before the thread is started.
[jit] Implement support for atomic intrinsics on arm.
[arm] Remove some unused code.