Define HAS_NEMO_RESOURCE as it's used in GStreamer code

I think embedlite does not use  NEMO_RESOURCE anymore, it has 
https://github.com/tmeshkova/gecko-dev/blob/embedlite/dom/media/gstreamer/GStreamerReader.cpp#L70
which require to export USE_NEMO_GSTREAMER=1 in order to use Nemo color converter
probably it make sense apply same changes to esr branch