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.
Add System.ServiceModel.Activation assembly. Fixes #14544
Don't emit inflated type parameter constraints which can collide with special constraint types.
Don't set sealed flag for imported static types
Bump ikvm
[runtime] Avoid direct access to MonoJitInfo.method, use an accessor function instead.
Extract the jit info table code into separate functions so we it can be used in more places.
[runtime] Make the address->aot module lookup in mono_jit_info_table_find () async-safe by storing the mapping in another MonoJitInfoTable.
[runtime] Add a lock-free mempool allocator to MonoDomain.
[runtime] Add a 'is_async_context' property to MonoThreadInfo, allowing functions to detect whenever they are in async context without having to pass an 'async' parameter around.
[runtime] Make mono_aot_find_jit_info () async-safe by allocating memory from the lock-free domain mempool, avoiding loading metadata, and caching jit info entries in a lock-free array.
[runtime] Make the stack walking code async safe when run in an async context.
[runtime] Make mono_install_handler_block_guard () async-safe. Fixes #14073.