pidgin/pidgin

Add a gtk-config-frame-cb property to PidginPluginInfo as it used to be there and some plugins were still trying to set it.

Testing Done:
ran in a devenv with `G_DEBUG=fatal-warnings gdb --args pidgin3` and verified that the program didn't halt on the gestures plugin anymore.

Reviewed at https://reviews.imfreedom.org/r/1090/
if get_option('doc')
subdir('libpurple')
subdir('protocols')
if ENABLE_GTK
subdir('pidgin')
else
pidgin_doc = []
endif
if enable_consoleui
subdir('finch')
else
finch_doc = []
endif
alias_target('doc', libpurple_doc, protocols_doc, pidgin_doc, finch_doc)
endif