Remove hosting methods that always return false (#9930)

* Remove CLRIoCompletionHosted as it always returns false.
* Remove CLRSyncHosted as it always returns false.
* Remove CLRMemoryHosted as it always returns false.
* Remove CLRTaskHosted as it always returns false.
* Remove CLRAssemblyHosted, CLRGCHosted,and CLRSecurityHosted.
They are not called.
* Remove IsThreadPoolHosted as it always returns false.
* Remove EnterRuntime and LeaveRuntime, as they do nothing.
* Add back calls to RevertIfImpersonated and GCX_PREEMP.

I accidentally deleted the call to RevertIfImpersonated instead of just
removing an extra parameter.

When I removed the HR_LEAVE_RUNTIME_HOLDER macro from windowsruntime.h,
I not only removed a LeaveRuntimeHolder but also a GCX_PREEMP. So I added
it back. The holder and GCX_PREEMP where only inserted when the
FEATURE_LEAVE_RUNTIME_HOLDER macro was defined. Since it is always defined,
I removed it. Also as I understand it, you would always want to have a
GCX_PREEMP before calling into the Windows API as not to block the GC,
so I'm not sure why you would want to disable it.

1 files changed, 1 insertions, 2 deletions

diff --git a/src/vm/threadsuspend.h b/src/vm/threadsuspend.h
index 428c914372..022e46a35e 100644
--- a/src/vm/threadsuspend.h
+++ b/src/vm/threadsuspend.h
@@ -92,8 +92,7 @@ struct SuspendStatistics
     // a Suspend to the end of a Restart.  We can compute 'avg' using 'cnt' and 'tot' values.
     MinMaxTot suspend, restart, paused;
 
-    // We know there can be contention on acquiring the ThreadStoreLock, or yield points when hosted (like
-    // BeginThreadAffinity on the leading edge and EndThreadAffinity on the trailing edge).
+    // We know there can be contention on acquiring the ThreadStoreLock.
     MinMaxTot acquireTSL, releaseTSL;
 
     // And if we OS suspend a thread that is blocking or perhaps throwing an exception and is therefore