made it so that ipc_stress_test doesn't get run with `build.sh tests`
diff --git a/aos/build/aos.gypi b/aos/build/aos.gypi
index 6f3364f..afbe6de 100644
--- a/aos/build/aos.gypi
+++ b/aos/build/aos.gypi
@@ -150,7 +150,11 @@
           ],
         }, {
           'variables': {
+            # Set this to 1 to disable rsyncing the file to the target.
             'no_rsync%': 0,
+            # Set this to 1 if this file isn't a test that should get run by
+            # `build.sh tests`.
+            'is_special_test%': 0,
           },
           'target_conditions': [
 # default to putting outputs into rsync_dir