abis_rsl: check if emergency calling is disabled before premption

If an emergency call arrives at the BSC while all TCH are busy, one TCH
is cleared in favor of the emergency call. However, if emergency calls
are disabled (system information), it is still possible that an MS might
try an emergency call anyway or that due to interference a regular call
might look like an emergency call (channel request reason). In those
cases the preemption must not happen and the emergency call must be
rejected.

Change-Id: I1af1f4fefcbe6a886bb5396901ce0cb2368a0e19
Related: OS#4976
1 file changed