Restore the use of "vpxor" instructions

previously "vpxor" instruction was mistakenly replaced by "aomor" as
port of vpx->aom renaming change. This commit revert that change for
where vpxor instruction should be used in asm code.

Change-Id: I411d95f5d8fa5ed380c8b0d6021118b6c1e9bfb9
diff --git a/third_party/libyuv/source/compare_win.cc b/third_party/libyuv/source/compare_win.cc
index 5e1e97b..19806f2 100644
--- a/third_party/libyuv/source/compare_win.cc
+++ b/third_party/libyuv/source/compare_win.cc
@@ -67,8 +67,8 @@
     mov        eax, [esp + 4]    // src_a
     mov        edx, [esp + 8]    // src_b
     mov        ecx, [esp + 12]   // count
-    aomor      ymm0, ymm0, ymm0  // sum
-    aomor      ymm5, ymm5, ymm5  // constant 0 for unpck
+    vpxor      ymm0, ymm0, ymm0  // sum
+    vpxor      ymm5, ymm5, ymm5  // constant 0 for unpck
     sub        edx, eax
 
   wloop:
diff --git a/third_party/libyuv/source/row_win.cc b/third_party/libyuv/source/row_win.cc
index 1e6033f..71be268 100644
--- a/third_party/libyuv/source/row_win.cc
+++ b/third_party/libyuv/source/row_win.cc
@@ -4855,7 +4855,7 @@
     mov        esi, [esp + 4 + 8]   // src_argb1
     mov        edx, [esp + 4 + 12]  // dst_argb
     mov        ecx, [esp + 4 + 16]  // width
-    aomor      ymm5, ymm5, ymm5     // constant 0
+    vpxor      ymm5, ymm5, ymm5     // constant 0
 
  convertloop:
     vmovdqu    ymm1, [eax]        // read 8 pixels from src_argb0
@@ -5535,7 +5535,7 @@
     vmovd      xmm5, eax  // low fraction 128..1
     vpunpcklbw xmm5, xmm5, xmm0
     vpunpcklwd xmm5, xmm5, xmm5
-    aomor      ymm0, ymm0, ymm0
+    vpxor      ymm0, ymm0, ymm0
     vpermd     ymm5, ymm0, ymm5
 
   xloop:
diff --git a/third_party/libyuv/source/scale_win.cc b/third_party/libyuv/source/scale_win.cc
index 74def62..c3896eb 100644
--- a/third_party/libyuv/source/scale_win.cc
+++ b/third_party/libyuv/source/scale_win.cc
@@ -240,7 +240,7 @@
     vpcmpeqb    ymm4, ymm4, ymm4      // '1' constant, 8b
     vpsrlw      ymm4, ymm4, 15
     vpackuswb   ymm4, ymm4, ymm4
-    aomor       ymm5, ymm5, ymm5      // constant 0
+    vpxor       ymm5, ymm5, ymm5      // constant 0
 
   wloop:
     vmovdqu     ymm0, [eax]
@@ -278,7 +278,7 @@
     vpcmpeqb    ymm4, ymm4, ymm4      // '1' constant, 8b
     vpsrlw      ymm4, ymm4, 15
     vpackuswb   ymm4, ymm4, ymm4
-    aomor       ymm5, ymm5, ymm5      // constant 0
+    vpxor       ymm5, ymm5, ymm5      // constant 0
 
   wloop:
     vmovdqu     ymm0, [eax]           // average rows
@@ -834,7 +834,7 @@
     mov         eax, [esp + 4]   // src_ptr
     mov         edx, [esp + 8]   // dst_ptr
     mov         ecx, [esp + 12]  // src_width
-    aomor       ymm5, ymm5, ymm5
+    vpxor       ymm5, ymm5, ymm5
 
   // sum rows
   xloop: