[reSIProcate] War on Warnings, late snow, setting -Werror

[Daniel Pocock]

This month we have late snow[1], my bike is in the garage and there were
no more excuses... I eliminated all the compiler warnings in both the
g++ and Clang builds.  This also included some tweaks for the headers we
use from sipXtapi.

In this build, there are no more warnings...

https://travis-ci.org/github/resiprocate/resiprocate/builds/771329711


Consequently, I set -Werror in CPPFLAGS for the travis-ci builds.  This
makes the build more strict.

>From now on, if anybody makes a commit or pull request including a
warning, builds in travis-ci will fail as if that was an error.

I've observed some builds failing[2] intermittently with a segmentation
fault.  This may be an issue in travis-ci.  I'll try to improve the
travis-ci log configuration to reveal a stack trace.

Regards,

Daniel


1.
https://www.meteosuisse.admin.ch/home/actualite/meteosuisse-blog/meteosuisse-blog.subpage.html/fr/data/blogs/2021/5/une-premiere-quinzaine-de-mai-fraiche.html
2. https://travis-ci.org/github/resiprocate/resiprocate/builds/771324663