pidgin/pidgin

Move purple_compat_date_time_format_iso8601 to just be a static inline with its normal glib name

Testing Done:
Compiled and ran locally. Also ran `ninja pidgin-pot libpurple-doc`

Reviewed at https://reviews.imfreedom.org/r/633/
---
name: libpurple-common
buildsystem: simple
build-commands:
- true
modules:
- external/avahi.yml
- external/cyrus-sasl2.yml
- external/farstream.yml
- external/libgadu.yml
- external/libidn.yml
- external/mercurial.yml
- gplugin.yml