Implements parsing of multi value User-Agent string. Fixes #8719
[runtime] Thread teardown race condition.  Fixes #13813.
Add another extension point to the runtime.
[System]: WebRequest.GetSystemProxy(): Return custom proxy for monodroid.

On ICS and newer, we can use Java.Net.ProxySelector, which supports
per-access point proxy settings.  Fixes #12640.
[sdb] Add support for invoking interface methods. Fixes #14503.
[runtime] Fix the mingw build by defining InterlockedCompareExchange64 () which is missing from mingw's winbase.h.
Don't print empty detailed assert message
[runtime] Force the usage of --host=i686-pc-mingw32 when running configure on windows.
Fixes parallel enumerable index counter. Fixes #14515
Cleanup TraceImpl
Set empty string to TraceListeners for empty assert message. Fixes #14505
[runtime] Fix a nullref when casting a null object to a complex type when using --debug=casts. Fixes #14552/#14493.
Suggestion fix for bug https://bugzilla.xamarin.com/show_bug.cgi?id=6327
[runtime] Make suspend work during thread cleanup. Fixes #14555

SDB does suspend/resume during thread cleanup. It used to work until I introduced
critical regions. This won't work anymore as we need to lookup the thread info object
and during cleanup it will be gone.

The fix is to introduce mono_thread_info_current_slow which is a variant of
mono_thread_info_current that does search the thread list if the TLS key
is gone.
[runtime] Fix a loader leak in the aot compiler.
Merge pull request #755 from ondrejmyska/master

Suggestion fix for bug https://bugzilla.xamarin.com/show_bug.cgi?id=6327
[verifier]Check generic constraints for duplicates. Fixes #1782.