correct mosquitto.h return code documentation

[martingkelly]

We currently erroneously claim that mosquitto_lib_init cannot fail,
while it can fail on Windows, if WSAStartup fails in net__init. Correct
this.

• Have you signed the Eclipse Contributor Agreement, using the same email address as you used in your commits?
• Do each of your commits have a "Signed-off-by" line, with the correct email address? Use "git commit -s" to generate this line for you.
• If you are contributing a bugfix, is your work based off the fixes branch?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run make test with your changes locally?
  "make test" is failing on my machine, but it fails identically on the fixes branch (on ./02-subscribe-qos1.py). As this changes only documentation, I highly doubt that's the issue.
  Test failure:

./02-subscribe-qos1.py c/02-subscribe-qos1-async2.test
connect_async failed: Connection refused
Traceback (most recent call last):
  File "./02-subscribe-qos1.py", line 47, in <module>
    (conn, address) = sock.accept()
  File "/usr/lib/python3.8/socket.py", line 292, in accept
    fd, addr = self._accept()
socket.timeout: timed out
make[2]: *** [Makefile:36: c] Error 1
make[2]: Leaving directory '/home/martin/ws/mosquitto/test/lib'
make[1]: *** [Makefile:11: test] Error 2
make[1]: Leaving directory '/home/martin/ws/mosquitto/test'
make: *** [Makefile:75: test] Error 2

---

[ralight]

Thank you.

Out of interest, what system are you running on? All the tests pass fine here, so it would be good to find the difference.

[martingkelly]

I'm running on Linux, and I never hit this issue at all. I found this out from code analysis rather than testing.

[ralight]

Sorry I wasn't sufficiently clear, I was referring to the ./02-subscribe-qos1.py c/02-subscribe-qos1-async2.test failure.

[martingkelly]

Ah, ok. My system is debian bullseye (testing):

martin@columbia:~$ cat /etc/os-release 
PRETTY_NAME="Debian GNU/Linux bullseye/sid"
NAME="Debian GNU/Linux"
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

[Alexbeckii]

Good