tr_image: store the fogNaive image as GL_RED, and fogLinear as GL_SR8_ET when available

Author: illwieckz

src/engine/renderer/tr_image.cpp

@@ -2446,11 +2446,6 @@ static void R_CreateFogImage()
 	imageParams.filterType = filterType_t::FT_DEFAULT;
 	imageParams.wrapType = wrapTypeEnum_t::WT_CLAMP;
 
-	if ( glConfig2.textureSrgbR8Available )
-	{
-		imageParams.bits |= IF_RED;
-	}
-
 	tr.fogImageNaive = R_CreateImage( "_fogNaive", ( const byte ** ) &data, FOG_S, FOG_T, 1, imageParams );
 
 	imageParams.bits |= IF_SRGB;

src/engine/renderer/tr_local.h

@@ -476,6 +476,7 @@ enum class ssaoMode {
 	  IF_DEPTH32 = BIT( 11 ),
 	  IF_PACKED_DEPTH24_STENCIL8 = BIT( 12 ),
 	  IF_LIGHTMAP = BIT( 13 ),
+	  IF_RED = BIT( 14 ),
 	  IF_RGBE = BIT( 15 ),
 	  IF_ALPHATEST = BIT( 16 ), // FIXME: this is unused
 	  IF_ALPHA = BIT( 17 ),