Set lightGrid point colour to r_forceAmbient after overbright shift

Avoid overflow and incorrect results due to the overbright shift.

Author: VReaperV

src/engine/renderer/tr_bsp.cpp

@@ -4124,19 +4124,19 @@ void R_LoadLightGrid( lump_t *l )
 		tmpDirected[ 2 ] = in->directed[ 2 ];
 		tmpDirected[ 3 ] = 255;
 
+		if ( tr.legacyOverBrightClamping )
+		{
+			R_ColorShiftLightingBytes( tmpAmbient );
+			R_ColorShiftLightingBytes( tmpDirected );
+		}
+
 		const byte forceAmbientNormalised = floatToUnorm8( r_forceAmbient.Get() );
 		if ( tmpAmbient[0] < forceAmbientNormalised &&
 			tmpAmbient[1] < forceAmbientNormalised &&
 			tmpAmbient[2] < forceAmbientNormalised ) {
 			VectorSet( tmpAmbient, forceAmbientNormalised, forceAmbientNormalised, forceAmbientNormalised );
 		}
 
-		if ( tr.legacyOverBrightClamping )
-		{
-			R_ColorShiftLightingBytes( tmpAmbient );
-			R_ColorShiftLightingBytes( tmpDirected );
-		}
-
 		for ( j = 0; j < 3; j++ )
 		{
 			ambientColor[ j ] = tmpAmbient[ j ] * ( 1.0f / 255.0f );