pidgin/pidgin

Add missing self-referential #include.

2020-11-20, Elliott Sales de Andrade
406ff566ad57
Add missing self-referential #include.

Fixes a function-without-prototype warning.

Testing Done:
Compile.

Reviewed at https://reviews.imfreedom.org/r/245/
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