Add private method NBLog::Reader::dumpLine()

This allows us to abstract out fdprintf vs ALOGI
so that callers don't need an 'if' at every location.

Change-Id: I4c68185fc19f32caeaed93347e6b7d09b8d4c4d8
Merge "Add private method NBLog::Reader::dumpLine()"
Merge remote-tracking branch 'aosp/master' into fml-master