[subscriber] Introduce subscr_put_channel

Introduce subscr_put_channel to release a channel and to
allow gsm_subscriber.c to hand this channel to any suitable
pending requests.
tree: 2aa2216456f817fcd8842989a45a21c0da727cad
  1. doc/
  2. tests/
  3. tools/
  4. AUTHORS
  5. configure.in
  6. COPYING
  7. Makefile.am
  8. README