pidgin/pidgin

Add underscore in Meson sources lists.

2020-12-29, Elliott Sales de Andrade
16127907763b
Add underscore in Meson sources lists.

Except for zephyr, which will be done in /r/302.

Testing Done:
Compile only.

Reviewed at https://reviews.imfreedom.org/r/312/
libpurple/data/purple-url-handler.desktop.in
libpurple/protocols/null/nullprpl.c
pidgin/data/im.pidgin.Pidgin.desktop.in
sub/libpurple/data/purple-url-handler.desktop.in
sub/libpurple/protocols/null/nullprpl.c
sub/pidgin/data/im.pidgin.Pidgin.desktop.in