Add missing coreclr check on JIT optimization

Add missing coreclr check on JIT optimization

* The JIT optimize the case where a LDFTN is followed by a NEWOBJ but
was missing the coreclr check (to avoid creating [SecurityCritical]
types, i.e. delegates).

Note that this does not affect moonlight since only three such user
visible types are affected and the API to use them is also marked with
[SecurityCritical]:
	System.ResolveEventHandler
	System.Threading.IOCompletionCallback
	System.UnhandledExceptionEventHandler