Upstream change I732234a22328a1bfcb603bb020547f543b6fd766 makes
RIL_UNSOL_DC_RT_INFO_CHANGED's responseFunction() NULL, without
protecting against it in RIL_onUnsolicitedResponse(), thus crash-
ing at least hammerhead's RIL stack upon mobile data connection.
https://android-review.googlesource.com/#/c/platform/hardware/ril/+/345950/
Change-Id: I6567019cb6daf6492a29e04cc9872e69b2ba456d
Signed-off-by: D. Andrei Măceș <Andrei.Maces@alumni.nd.edu>
(cherry picked from commit e73eafff8695ab28201acbc03a362d5b177047aa)