TODO: remove armv7 setting

Leave a TODO note in build/common.gypi to remove this obsolete armv7
setting, once all uses of it are removed.

BUG=234135

Review URL: https://codereview.chromium.org/103203002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@238643 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -519,6 +519,8 @@
         }],
 
         # Set armv7 for backward compatibility.
+        # TODO(mostynb@opera.com): remove armv7 once all uses are
+        # removed http://crbug.com/234135
         ['arm_version==7', {
           'armv7': 1,
         }, {