Update pddm to work with clang-format

Add clang-format off/on directives around pddm expansions to simplify formatting other code.
diff --git a/objectivec/DevTools/pddm_tests.py b/objectivec/DevTools/pddm_tests.py
index 6aa60f9..8184209 100755
--- a/objectivec/DevTools/pddm_tests.py
+++ b/objectivec/DevTools/pddm_tests.py
@@ -394,6 +394,7 @@
 class TestProcessingSource(unittest.TestCase):
 
   def testBasics(self):
+    self.maxDiff = None
     input_str = u"""
 //%PDDM-IMPORT-DEFINES ImportFile
 foo
@@ -417,18 +418,24 @@
 foo
 //%PDDM-EXPAND mumble(abc)
 // This block of code is generated, do not edit it directly.
+// clang-format off
 
 abc: doAbc(int abc);
+// clang-format on
 //%PDDM-EXPAND-END mumble(abc)
 bar
 //%PDDM-EXPAND mumble(def)
 // This block of code is generated, do not edit it directly.
+// clang-format off
 
 def: doDef(int def);
+// clang-format on
 //%PDDM-EXPAND mumble(ghi)
 // This block of code is generated, do not edit it directly.
+// clang-format off
 
 ghi: doGhi(int ghi);
+// clang-format on
 //%PDDM-EXPAND-END (2 expansions)
 baz
 //%PDDM-DEFINE mumble(a_)