PixelShaderGen: Use integer math for alpha testing.

Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp

@@ -463,6 +463,9 @@ void ProgramShaderCache::CreateHeader ( void )
 		"#define float2 vec2\n"
 		"#define float3 vec3\n"
 		"#define float4 vec4\n"
+		"#define uint2 uvec2\n"
+		"#define uint3 uvec3\n"
+		"#define uint4 uvec4\n"
 		"#define int2 ivec2\n"
 		"#define int3 ivec3\n"
 		"#define int4 ivec4\n"