* Some man pages to write.
* Rewrite embedded mpglib code to instead link against libmpg123
  <https://www.mpg123.de/asterisk.shtml>
* Get libilbc packages instead of the built-in libilbc.
* Maybe install phoneprov files below /etc - they seem use editable
* install upstream dahdi span_config file
  * add patch to un-duplicate file
  * verify that switching execution 50 -> 40 is not a problem
* Patch upstream to install missed manpages:
  * doc/aelparse.8
  * doc/smsq.8
  * utils/astman.1
* maybe use configure option --disable-binary-modules
  instead of custom download avoidance
* maybe set configure environment variable LUA_VERSIONS
