libmedia2_jni: link to libcgrouprc

libcgrouprc is an LLNDK library used by libprocessgroup.
libprocessgroup is linked statically, so the dependency needs
to be explicitly stated in libmedia2_jni.

Test: boots (sanity)
Bug: 123664216
Change-Id: Ieebba36417d1f83a5946f927043f15dc8abc188a