StrictMode: avoid an allocation in common case

Make the initialValue() of the ThreadLocal be null, so checking it doesn't
cause one to be created in the case of an RPC call not using StrictMode.

Change-Id: I3ea19ce444a1b3c39a6e53c5cb5d4faf4b07a6c8
diff --git a/core/java/android/os/Parcel.java b/core/java/android/os/Parcel.java
index bfe3b60..b9c9565 100644
--- a/core/java/android/os/Parcel.java
+++ b/core/java/android/os/Parcel.java
@@ -1202,6 +1202,7 @@
             code = EX_ILLEGAL_STATE;
         }
         writeInt(code);
+        StrictMode.clearGatheredViolations();
         if (code == 0) {
             if (e instanceof RuntimeException) {
                 throw (RuntimeException) e;