Check for features.h.
* configure.in, config.h.in: Check for features.h. * gdk/gdkevents.c (gdk_event_put, gdk_events_queue): Fixed bug in linked list append logic by replacing hand-coded logic with a call to g_list_append. Bug found by tml. * gdk/gdkimage.c: 'gcc -ansi -pedantic' on GNU/Linux spews warnings and errors in sys/ipc.h, including one specific admonishment to use _SVID_SOURCE or _XOPEN_SOURCE. Manually defined the latter, and included features.h if present to obtain the necessary side-effects. * gtk/gtkclist.c, gtk/gtkeditable.c: Eliminates comma-after-final-element warnings. * gtk/gtkfontsel.c (gtk_font_selection_init): Fixed bug where an intl string was declared as _("x") in local var initializer.