Revert of WAE on Macs too.  That leaves only Android framework builds. (patchset #3 id:40001 of https://codereview.chromium.org/804063002/)

Reason for revert:
Forgot CrOS and NaCl builds.

Original issue's description:
> WAE on Macs too.  That leaves only Android framework builds.
>
> Will rebase after yours lands.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/161b6dee11a67e877ef5b339b17775b8e44c5927

TBR=bsalomon@google.com,mtklein@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/805043002
diff --git a/gyp/common_variables.gypi b/gyp/common_variables.gypi
index c33defc..67b40a5 100644
--- a/gyp/common_variables.gypi
+++ b/gyp/common_variables.gypi
@@ -161,10 +161,12 @@
     },
 
     'conditions': [
-      [ 'skia_android_framework', {
-        'skia_warnings_as_errors%': 0,
-      }, {
+      [ 'skia_os in ["linux", "freebsd", "openbsd", "solaris", "android", "win"] '
+            'and skia_android_framework == 0 or '
+        'skia_os == "mac" and skia_arch_width == 32', {
         'skia_warnings_as_errors%': 1,
+      }, {
+        'skia_warnings_as_errors%': 0,
       }],
 
       # This variable allows the user to customize the optimization level used