libvpx: Pull from upstream

libvpx_srcs_x86_intrinsics.gypi

Index: libvpx_srcs_x86_intrinsics.gypi
===================================================================
--- libvpx_srcs_x86_intrinsics.gypi	(revision 240222)
+++ libvpx_srcs_x86_intrinsics.gypi	(working copy)
@@ -77,5 +77,26 @@
         }],
       ],
     },
+    {
+      'target_name': 'libvpx_intrinsics_avx2',
+      'type': 'static_library',
+      'include_dirs': [
+        'source/config/<(OS_CATEGORY)/<(target_arch)',
+        '<(libvpx_source)',
+      ],
+      'sources': [
+        '<(libvpx_source)/vp9/common/x86/vp9_loopfilter_intrin_avx2.c',
+      ],
+      'conditions': [
+        ['os_posix==1 and OS!="mac"', {
+          'cflags': [ '-mavx2', ],
+        }],
+        ['OS=="mac"', {
+          'xcode_settings': {
+            'OTHER_CFLAGS': [ '-mavx2', ],
+          },
+        }],
+      ],
+    },
   ],
 }