cel_pgsql: module not correctly reloading

Upon reload the module unconditionally "unloaded" the module (freeing memory
and setting pointers to NULL) and then when attempting a "load" if the config
file had not changed then nothing would be reinitialized.

By moving the "unload" to occur conditionally (reload only) after an attempted
configuration load, but before module "loading" alleviates the issue. The module
now loads/unloads/reloads correctly.

(closes issue ASTERISK-22871)
Reported by: Matteo
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Merged revisions 404857 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 404858 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 404859 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@404860 65c4cc65-6c06-0410-ace0-fbb531ad65f3