configure.ac: Bump liboil requirement to 0.3.8.
Original commit message from CVS: * configure.ac: Bump liboil requirement to 0.3.8. * gst-libs/gst/riff/riff-media.c: Add Dirac fourcc. * gst/videoscale/vs_image.h: * gst/videoscale/vs_scanline.h: Use liboil's stdint.h. * gst/videotestsrc/videotestsrc.c: Remove liboil related ifdef's, since they aren't needed now, and won't work with future versions.