subscriber: Address coverity warning and truncate the IMSI

The IMSI can only be 15 characters in length, our define gives
us a length of 17. This means we have place for two NULs. Use
strncpy and make sure it is null-terminated.

Fixes: Coverity CID 1040707
1 file changed
tree: 19ed8f4c09980aa3574b30985bbb890b76a761d4
  1. debian/
  2. hlrsync/
  3. linux-kernel/
  4. openbsc/
  5. wireshark/
  6. README