* conf files

Decide on if a mosquitto config file should be installed in etc, or if
a user should take a few lines from the (large) example as needed.

Document our strategy for modifying the example file, explaining if it
is reflecting compiled-in defaults, or some other reasons.

* patches

For each, document why and file upstream/include ref or explain why
upstream is inappropriate.

** ldconfig

Upstream appears to run ldconfig on "UNIX", which is incorrect.  File
a bug about this.

* security

Check if these are really fixed in 1.5.1:
  https://nvd.nist.gov/vuln/detail/CVE-2017-7653
  https://nvd.nist.gov/vuln/detail/CVE-2017-7654

Query sent to list on 20180904.  It seems likely that they are fixed
but that it is not clearly documented.
