Convert a few inner loops to use liboil.  This is currently optional, and is only enabled if liboil is present (duh!).

Original commit message from CVS:
Convert a few inner loops to use liboil.  This is currently
optional, and is only enabled if liboil is present (duh!).
* configure.ac: Check for liboil-0.1
* gst/intfloat/Makefile.am:
* gst/intfloat/gstint2float.c: (conv_f32_s16), (scalarmult_f32),
(gst_int2float_chain_gint16):
* gst/videofilter/Makefile.am:
* gst/videofilter/gstvideobalance.c: (gst_videobalance_class_init),
(tablelookup_u8), (gst_videobalance_planar411):
* gst/videotestsrc/Makefile.am:
* gst/videotestsrc/gstvideotestsrc.c: (plugin_init):
* gst/videotestsrc/videotestsrc.c: (splat_u8), (paint_hline_YUY2),
(paint_hline_IYU2), (paint_hline_str4), (paint_hline_str3),
(paint_hline_RGB565), (paint_hline_xRGB1555):