pidgin/pidgin

Credit Evert Mouw for the portion of his PR that I accepted.
winprefs_SOURCES = [
'gtkappbar.c',
'gtkappbar.h',
'winprefs.c'
]
winprefs = library('winprefs', winprefs_SOURCES,
dependencies : [libpurple_dep, libpidgin_dep, glib],
name_prefix : '',
install : true, install_dir : PIDGIN_PLUGINDIR)