[gn] Switch off gyp in runhooks by default

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index b93b79d918fa7ab22cc28ac89628d6dd1c2c1817..0844c1209038a7736d3e82c0efa5fadfb3f55b78 100644
--- a/DEPS
+++ b/DEPS
@@ -279,6 +279,6 @@ hooks = [
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
-    "action": ["python", "v8/gypfiles/gyp_v8"],
+    "action": ["python", "v8/gypfiles/gyp_v8", "--running-as-hook"],
   },
 ]