Disable vp8_sixtap_predict4x4_neon

Crashing on iOS encodes
BUG=817

Change-Id: I2c50f8d359563d15a8b8002b6091184c0f9818af

vp8/common/rtcd_defs.pl

@@ -220,7 +220,8 @@ $vp8_sixtap_predict8x4_media=vp8_sixtap_predict8x4_armv6;
 $vp8_sixtap_predict8x4_dspr2=vp8_sixtap_predict8x4_dspr2;
 
 add_proto qw/void vp8_sixtap_predict4x4/, "unsigned char *src, int src_pitch, int xofst, int yofst, unsigned char *dst, int dst_pitch";
-specialize qw/vp8_sixtap_predict4x4 mmx ssse3 media neon dspr2/;
+# Disable neon while investigating https://code.google.com/p/webm/issues/detail?id=817
+specialize qw/vp8_sixtap_predict4x4 mmx ssse3 media dspr2/;
 $vp8_sixtap_predict4x4_media=vp8_sixtap_predict4x4_armv6;
 $vp8_sixtap_predict4x4_dspr2=vp8_sixtap_predict4x4_dspr2;