keepalive: fix initialization when using destination mod param

[NGSegovia]

• Fixed the way the module is initialized, causing problems when using
  destination mod parameter because when invoking this parameter some
  utilities are not initialized (timers).

Pre-Submission Checklist

• Commit message has the format required by CONTRIBUTING guide
• Commits are split per component (core, individual modules, libs, utils, ...)
• Each component has a single commit (if not, squash them into one commit)
• No commits to README files for modules (changes must be done to docbook files
  in doc/ subfolder, the README file is autogenerated)

Type Of Change

• Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)

Checklist:

• PR should be backported to stable branches
• Tested changes locally
• Related to issue Kamailio-5.4.: Crashs from keepalive module during adding destination #2476 (replace XXXX with an open issue number)

Description

Fixed the way the module is initialized, causing problems when using destination mod parameter because when invoking this parameter some utilities are not yet initialized (timers).

[miconda]

Regarding the Coding style/C standard requirements, I started a discussion several months ago to see what people/devs consider to be better to use:

• https://lists.kamailio.org/pipermail/sr-users/2020-April/109072.html

Kamailio being used in various embedded devices, with stricter compilers, in terms of declaring variables, they have to be at least at the beginning of the block, although now I also prefer at the beginning of functions, since we guide mainly after C89 (which was the implemented in compilers when project was started in 2000).

On PR, I haven't done any extensive review, but if no other comments, it can be merged.

[NGSegovia]

Regarding the Coding style/C standard requirements, I started a discussion several months ago to see what people/devs consider to be better to use:

• https://lists.kamailio.org/pipermail/sr-users/2020-April/109072.html

Kamailio being used in various embedded devices, with stricter compilers, in terms of declaring variables, they have to be at least at the beginning of the block, although now I also prefer at the beginning of functions, since we guide mainly after C89 (which was the implemented in compilers when project was started in 2000).

On PR, I haven't done any extensive review, but if no other comments, it can be merged.

Cristal clear, thanks for the explanation Daniel!