Add SK_IGNORE_MAC_OPSZ_FORCE to hold out Skia change.

Skia is planning to change how the CTFont is created for glyph metrics
and drawing. As a result there will be some changes to layout tests.
Hold out the Skia side changes until the tests can be updated.

Change-Id: I807591eba700c7af3e20c5e234af06d16155a742
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2068829
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Ben Wagner <bungeman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744033}

skia/BUILD.gn

@@ -134,7 +134,10 @@ config("skia_library_config") {
     defines += [ "SK_FREETYPE_MINIMUM_RUNTIME_VERSION=(((FREETYPE_MAJOR) * 0x01000000) | ((FREETYPE_MINOR) * 0x00010000) | ((FREETYPE_PATCH) * 0x00000100))" ]
   }
 
-  defines += [ "SKIA_IMPLEMENTATION=1" ]
+  defines += [
+    "SKIA_IMPLEMENTATION=1",
+    "SK_IGNORE_MAC_OPSZ_FORCE",
+  ]
 
   if (current_cpu == "arm") {
     if (arm_use_neon) {