Move GetAverageLuminance() to the correct ifdef

Author: VReaperV

src/engine/renderer/glsl_source/cameraEffects_fp.glsl

@@ -57,11 +57,12 @@ vec3 TonemapLottes( vec3 color ) {
 	layout(std140, binding = BIND_LUMINANCE) uniform ub_LuminanceUBO {
 		uint luminanceU;
 	};
+
+	float GetAverageLuminance( const in uint luminance ) {
+		return float( luminanceU ) / ( u_TonemapParms2[1] * u_ViewWidth * u_ViewHeight );
+	}
 #endif
 
-float GetAverageLuminance( const in uint luminance ) {
-    return float( luminanceU ) / ( u_TonemapParms2[1] * u_ViewWidth * u_ViewHeight );
-}
 #endif
 
 DECLARE_OUTPUT(vec4)