pidgin/pidgin

simple: Fix search for message headers.

2020-05-17, Elliott Sales de Andrade
f38b64939ecb
simple: Fix search for message headers.

The list contains key-value pairs (of `PurpleKeyValuePair` type now, but
`struct siphdrelement` before) so using `g_ascii_strcasecmp` directly
does not work.
For information on translating Pidgin, libpurple, and Finch, please see
our wiki page at https://developer.pidgin.im/wiki/TipsForTranslators