Reactor: Add address-of operator on reference types.

Allows expressions like:

Array<Float4> arr;
Pointer<Float4> ptr = &arr[0];

Bug: b/126330097
Change-Id: I4ad95b46cfa1332eded0424ba4aeb7fe8642b71a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/25709
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>

src/Reactor/Reactor.hpp

@@ -114,6 +114,8 @@ namespace rr
 
 		RValue<T> operator+=(RValue<T> rhs) const;
 
+		RValue<Pointer<T>> operator&() const { return RValue<Pointer<T>>(address); }
+
 		Value *loadValue() const;
 		int getAlignment() const;