PRESUBMIT: Add iOS ARM64 trybots to default set.

BUG=chromium:436831
TBR=phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/25319004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7822 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 14bc50b..0243267 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -295,6 +295,8 @@
   ] + android_gn_bots
   ios_bots = [
       'ios',
+      'ios_arm64',
+      'ios_arm64_rel',
       'ios_rel',
   ]
   linux_gn_bots = [