Enable NEON functions for ARM32
Enable NEON functions for ARM32

In init functions, whether the code of NEON initialization is compiled
is decided by macros HAS_XXXX_NEON. These macros HAS_XXXX_NEON are defined
according to __ARM_NEON__/LIBYUV_NEON/__aarch64__. For ARM32, "-mfpu=neon"
isn't passed to the files containing init functions. So __ARM_NEON__ is
undefined which leads to NEON functions are disabled.
In this patch, LIBYUV_NEON is added to enable HAS_XXXX_NEON definition for ARM32.

BUG=none
TESTED=libyuv_unittest on android of ARM32/ARM64
R=fbarchard@google.com

Change-Id: Ib4201e7152d2aeb0ba80d18bbbd0487151e4564e

Review URL: https://webrtc-codereview.appspot.com/32959004
alfahim/libyuv,VladDrake/libyuv,fate-extra/libyuv,dexcz/libyuv,aberejohn/libyuv,syoshimu/libyuv,hajunho/libyuv,hyper123/libyuv,KerwinMa/libyuv,sathishkumars3/libyuv,yzhikan/libyuv,yzhikan/libyuv,aberejohn/libyuv,uditkumawat/libyuv,bingerZhang/libyuv,ganzhijie/libyuv,wl-chuang/libyuv,chucvv/libyuv,alfahim/libyuv,OrenHg/libyuv,bingerZhang/libyuv,uditkumawat/libyuv,dexcz/libyuv,mosterta/libyuv,dilagurung/libyuv,syoshimu/libyuv,wl-chuang/libyuv,VladDrake/libyuv,hajunho/libyuv,syoshimu/libyuv,OrenHg/libyuv,yzhikan/libyuv,alfahim/libyuv,ganzhijie/libyuv,aberejohn/libyuv,chucvv/libyuv,uraran/libyuv,bingerZhang/libyuv,StopProducing/libyuv,ganzhijie/libyuv,KerwinMa/libyuv,StopProducing/libyuv,OrenHg/libyuv,Vairn/libyuv,RockySteveJobs/libyuv,gigakuma/libyuv,fate-extra/libyuv,skufog/libyuv,gigakuma/libyuv,sathishkumars3/libyuv,dilagurung/libyuv,WangYongHai/libyuv,hyper123/libyuv,mosterta/libyuv,RockySteveJobs/libyuv,Vairn/libyuv,skufog/libyuv,WangYongHai/libyuv,gigakuma/libyuv,Vairn/libyuv,hajunho/libyuv,WangYongHai/libyuv,uraran/libyuv,StopProducing/libyuv,skufog/libyuv,KerwinMa/libyuv,chucvv/libyuv,mosterta/libyuv,wl-chuang/libyuv,fate-extra/libyuv,sathishkumars3/libyuv,hyper123/libyuv,dilagurung/libyuv,uditkumawat/libyuv,uraran/libyuv,dexcz/libyuv,RockySteveJobs/libyuv,VladDrake/libyuv