SL-17682: PBR: Fix debug fresnel roughness output to match glTF Sample Viewer

indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl

@@ -395,6 +395,7 @@ void main()
     #endif
     #if DEBUG_PBR_FRESNEL
         color.rgb = fresnelR;
+        color.rgb = srgb_to_linear(color.rgb);
     #endif
     #if DEBUG_PBR_IOR
         color.rgb = vec3(IOR);