pidgin/pidgin

Some zephyr cleanups

2020-12-03, Arkadiy Illarionov
1f8b5b68a806
Some zephyr cleanups

* Replace macros with inline functions.
* Move duplicated code to functions.
* Use purple_strequal() and purple_str_has_caseprefix() where applicable.
* Remove unneeded variables.
* Remove unused header.

Testing Done:
Compiled with internal and external libzephyr.

Reviewed at https://reviews.imfreedom.org/r/260/
[main]
host = https://www.transifex.com
[pidgin.pidgin_pot-for-development-branch]
file_filter = po/<lang>.po
source_file = po/pidgin.pot
source_lang = en