Stats: track how frequently contact images are present incall

For retail devices (and installer builds), introduce tags to be read
by a separate, additional, package.

This will not be read or collected in any community (nightly/M/etc) or
self-built build.

Change-Id: I7f52f18a53ade50e0274af633cb7c26566332ee7
Merge branch 'cm' into HEAD

Signed-off-by: DHOMD <DHO@dho.im>

Conflicts:
	src/com/android/incallui/ContactInfoCache.java

Change-Id: Iebd35d30dff4fb1cc3cd02113e6637a56d291f36