Added UInt to FP cast

UInt4 -> Float4 already existed, but not UInt -> Float.

Added the scalar conversion code and used it in the
Blitter where appropriate.

Change-Id: I9ebf63fdf8b139b960237b269f2da088f6ecac86
Reviewed-on: https://swiftshader-review.googlesource.com/10888
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/Reactor/Reactor.hpp b/src/Reactor/Reactor.hpp
index b02c6be..186f739 100644
--- a/src/Reactor/Reactor.hpp
+++ b/src/Reactor/Reactor.hpp
@@ -1535,6 +1535,7 @@
 	{
 	public:
 		explicit Float(RValue<Int> cast);
+		explicit Float(RValue<UInt> cast);
 
 		Float() = default;
 		Float(float x);