Enable VP8 & VP9 decoder and add patch related with VP8 & VP9

Enable VP8 & VP9 decoder and add patch related with VP8 & VP9

[Enable]
--enable-parser=vp8 --enable-decoder=vp8 --enable-decoder=vp9

[Patch]
arm: use a local label instead of the function symbol in ff_prefetch_arm
Avoids a relocation which might end out of range for thumb2.

Reported-By: Ludovic Fauvet <etix@videolan.org>
Bug-Id: https://bugs.webkit.org/show_bug.cgi?id=137022
CC: libav-stable@libav.org
Change-Id: Id4c2acac8f150f81df654fffccde6433d68869ff
Signed-off-by: jiyong.min <jiyong.min@samsung.com>
(cherry picked from commit cd3ed69efc06591c75a0a3fd62a28092791cd72d)