Fix Delegate Equals() method

[mattwarren]

Simple fix for the underlying issue of the bug described here:

// because the DotNetAnywhere runtime crashes if you try to put a delegate instance
// as a key into a Dictionary and then check whether dict.ContainsKey(thatDelegate).

Tested with code like this:

Action actionA = new Action(TestMethod);
Action actionB = new Action(SomeOtherMethod);
Action actionC = new Action(TestMethod); // same Target as actionA

// Before the fix calling 'Equals() give the error "Opcode not available: 0x0000006c"
Console.WriteLine("actionA.Equals(actionB) = {0}", actionA.Equals(actionB)); // False
Console.WriteLine("actionA.Equals(actionC) = {0}", actionA.Equals(actionC)); // True

To properly allow DNA to handle boxing/unboxing of IntPtr, support would have to be added for:

• JIT_BOX_PTR (probably here)
• UNBOX CIL op-code (CIL_UNBOX_ANY is already supported)