Ignore arm_neon_optional if arm_neon==1 in skia.

BUG=451035

Review URL: https://codereview.chromium.org/1135693008

Cr-Commit-Position: refs/heads/master@{#330512}

skia/BUILD.gn

@@ -202,8 +202,7 @@ config("skia_library_config") {
   if (current_cpu == "arm") {
     if (arm_use_neon) {
       defines += [ "SK_ARM_HAS_NEON" ]
-    }
-    if (arm_optionally_use_neon) {
+    } else if (arm_optionally_use_neon) {
       defines += [ "SK_ARM_HAS_OPTIONAL_NEON" ]
     }
   }

skia/skia_common.gypi

@@ -99,7 +99,7 @@
         'SK_ARM_HAS_NEON',
       ],
     }],
-    [ 'target_arch == "arm" and arm_version >= 7 and arm_neon_optional == 1', {
+    [ 'target_arch == "arm" and arm_version >= 7 and arm_neon == 0 and arm_neon_optional == 1', {
       'defines': [
         'SK_ARM_HAS_OPTIONAL_NEON',
       ],