SL-9711 modify clamping range on atmospheric additive color to balance between maintaining old look of WL settings and fixing SL1491 lens flare bug

indra/newview/app_settings/shaders/class2/windlight/atmosphericsVarsV.glsl

@@ -75,7 +75,7 @@ void setAdditiveColor(vec3 v)
 {
     // SL-1491 clamp additive term to something reasonable to prevent
     // lens flares over non-reflective surfaces
-    v = clamp(v, vec3(0), vec3(0.2));
+    v = clamp(v, vec3(0), vec3(0.8));
 	additive_color = v;
 	vary_AdditiveColor = v;
 }