VideoCommon/TextureCacheBase: Remove dependence on global variables from OnConfigChanged()

The active config will always be passed as the reference parameter, we
can make use of the parameter instead of accessing the global variable.

Source/Core/VideoCommon/TextureCacheBase.cpp

@@ -155,9 +155,7 @@ void TextureCacheBase::OnConfigChanged(const VideoConfig& config)
       config.bArbitraryMipmapDetection != backup_config.arbitrary_mipmap_detection)
   {
     Invalidate();
-
-    TexDecoder_SetTexFmtOverlayOptions(g_ActiveConfig.bTexFmtOverlayEnable,
-                                       g_ActiveConfig.bTexFmtOverlayCenter);
+    TexDecoder_SetTexFmtOverlayOptions(config.bTexFmtOverlayEnable, config.bTexFmtOverlayCenter);
   }
 
   SetBackupConfig(config);