Fixed Windows warnings

- Removed unused variables
- Removed unreachable code
- Fixed size_t <-> int conversions
- Fixed uninitialized variables

Change-Id: Ifc3912e92b8f0710094e939bd0da4757148b559a
Reviewed-on: https://swiftshader-review.googlesource.com/5681
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
diff --git a/src/OpenGL/libGLESv2/utilities.cpp b/src/OpenGL/libGLESv2/utilities.cpp
index 9d22290..841bcab 100644
--- a/src/OpenGL/libGLESv2/utilities.cpp
+++ b/src/OpenGL/libGLESv2/utilities.cpp
@@ -776,7 +776,7 @@
 			return error(GL_INVALID_ENUM, false);
 		}
 
-		if(internalformat != format)
+		if((GLenum)internalformat != format)
 		{
 			if(clientVersion < 3)
 			{
@@ -993,7 +993,7 @@
 
 		#undef VALIDATE_INTERNALFORMAT
 
-		if(internalformat != format && !validSizedInternalformat)
+		if((GLenum)internalformat != format && !validSizedInternalformat)
 		{
 			return error(GL_INVALID_OPERATION, false);
 		}