liblog: add xlog include from karfield/adb

Change-Id: Ib29fee48456912649983a7a5002c0c013208bec6
liblog: slight adaptations for xlog.h

Change-Id: Id7614b672bbf99e2b70d5e4cd922d5cfd33942e2
liblog: add stubs for xlog functions

Change-Id: Iea64ce251ad532fa7d143589650eeea9079b6939
Merge branch 'add-stub-xlog' into cm-11.0