libmix: optimize search start code function in h264

BZ: 189364

optimize search start code ASM function in h264,
if 0 occurs 15, 13, 12, 11 ....3, 1 byte, do not jump out from the loop
immediately, check 15,14,12,....2, 1 byte, if no 0 occurs in these position,
it's impossible to have 0x010000 at these 16 byte.

Change-Id: Ie58776c164d499ec3860e190786a11a9191ec7df
Signed-off-by: ywan171 <yi.a.wang@intel.com>
1 file changed