Allow users to specify the encoder used for framedumping.

Source/Core/VideoCommon/VideoConfig.cpp

@@ -84,6 +84,7 @@ void VideoConfig::Refresh()
   bUseFFV1 = Config::Get(Config::GFX_USE_FFV1);
   sDumpFormat = Config::Get(Config::GFX_DUMP_FORMAT);
   sDumpCodec = Config::Get(Config::GFX_DUMP_CODEC);
+  sDumpEncoder = Config::Get(Config::GFX_DUMP_ENCODER);
   sDumpPath = Config::Get(Config::GFX_DUMP_PATH);
   iBitrateKbps = Config::Get(Config::GFX_BITRATE_KBPS);
   bInternalResolutionFrameDumps = Config::Get(Config::GFX_INTERNAL_RESOLUTION_FRAME_DUMPS);