ARGBExtractAlphaRow_Any_AVX2 fix pixel count mask

Mask was set to 32, but should have been 31.
BUG=libyuv:798
TESTED=try bots tested

Change-Id: I6120928873a4a2f1efef907d8e8296ca8c20bb03
Reviewed-on: https://chromium-review.googlesource.com/1054830Reviewed-by: Frank Barchard <fbarchard@chromium.org>

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 1709
+Version: 1710
 License: BSD
 License File: LICENSE
 

include/libyuv/version.h

@@ -11,6 +11,6 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 1709
+#define LIBYUV_VERSION 1710
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_

source/row_any.cc

@@ -673,7 +673,7 @@ ANY11(ARGBAttenuateRow_Any_MSA, ARGBAttenuateRow_MSA, 0, 4, 4, 7)
 ANY11(ARGBExtractAlphaRow_Any_SSE2, ARGBExtractAlphaRow_SSE2, 0, 4, 1, 7)
 #endif
 #ifdef HAS_ARGBEXTRACTALPHAROW_AVX2
-ANY11(ARGBExtractAlphaRow_Any_AVX2, ARGBExtractAlphaRow_AVX2, 0, 4, 1, 32)
+ANY11(ARGBExtractAlphaRow_Any_AVX2, ARGBExtractAlphaRow_AVX2, 0, 4, 1, 31)
 #endif
 #ifdef HAS_ARGBEXTRACTALPHAROW_NEON
 ANY11(ARGBExtractAlphaRow_Any_NEON, ARGBExtractAlphaRow_NEON, 0, 4, 1, 15)