build: add support for automake 1.13
build: add support for automake 1.13

In Automake 1.13, the long-deprecated macro AM_CONFIG_HEADER (deprecated
since 2002) has been removed in favour of AC_CONFIG_HEADERS.

lubosz/clutter-gst,ystreet/clutter-gst,GNOME/clutter-gst,ystreet/clutter-gst,GNOME/clutter-gst,lubosz/clutter-gst,lubosz/clutter-gst,GNOME/clutter-gst,ystreet/clutter-gst,ystreet/clutter-gst,GNOME/clutter-gst