Port of all JIT changes for .NET Framework 4.6.1 changes

Port of all JIT changes for .NET Framework 4.6.1 changes
    http://blogs.msdn.com/b/dotnet/archive/2015/11/30/net-framework-4-6-1-is-now-available.aspx

.NET Framework list of changes in 4.6.1
    https://github.com/Microsoft/dotnet/blob/master/releases/net461/dotnet461-changes.md

Additional changes including
-    Working ARM64 JIT compiler
-    Additional JIT Optimizations
     o    Tail call recursion optimization
     o    Array length tracking optimization
     o    CSE for widening casts
     o    Smaller encoding for RIP relative and absolute addresses in addressing modes
     o    Tracked Local Variable increased to 512
     o    Improved handling of Intrinsics System.GetType()
     o    Improved handling of Math intrinsics
-    Work for the X86 Ryu-JIT compiler

[tfs-changeset: 1557101]