Add RLOGx

This will eventually allow us to remove the code in
logd_write.c#__android_log_write which uses the tag
to direct logs to the radio buffer.

Change-Id: I7a6a966bc12e59a3ec68a56a41dd681fb325dfd8

Conflicts:
	reference-ril/atchannel.c
	reference-ril/reference-ril.c
	rild/rild.c