Fix incorrect ifdef for subgroup atomics

Author: VReaperV

src/engine/renderer/glsl_source/luminanceReduction_cp.glsl

@@ -74,7 +74,7 @@ void main() {
 
     const float luminance = ColorToLuminance( texelFetch( renderImage, position, 0 ).rgb );
 
-	#if defined(HAVE_subgroup_atomic)
+	#if defined(SUBGROUP_ATOMIC)
 		const float luminanceSum = subgroupInclusiveAdd( luminance );
 
 		if( subgroupElect() ) {