Bareos-director segfaults on startup

Bareos in alpine >= 3.9 segfaults on startup.
The issue is the “bsmtp” program which fails and tears down the whole director.

Reproducible with:

$>docker run -it alpine:3.9 /bin/ash
/ # apk add bareos
[…]
/ # bsmtp
Segmentation fault (core dumped)

(from redmine: issue id 10156, created on 2019-03-26, closed on 2019-04-08)

• Changesets:
  • Revision 1b3fe8f6 by Simon F on 2019-04-08T18:23:45Z:

community/bareos: Fix segfaults on startup

This PR fixes two undefined behaviours with pthreads leading to
segfaults.

Fixes #10156
https://bugs.alpinelinux.org/issues/10156

(cherry picked from commit 37923bd0f6d4e33a3b7de6c23e708787c5d7d3bf)