define WEBP_USE_INTRINSICS w/gcc-4.9+

32-bit builds are neutral to slightly faster using ndk r15c on a
N5/S6/CM1

BUG=webp:339

Change-Id: I94b9442e0ceaf2f5edb2b4026bc8b99cd77c918b
(cherry picked from commit 01c426f1e7bd83e6a6f86d77f08103d1dca1f2af)
1 file changed