Hide android.os.Parcel.obtain(int).

This will break on 64 bit because 64 bit pointers are
wider than java int.

Also, this method technically isn't a public API because
it's a protected method on a final class. It shows up in
our api.txt files because of a quirk in the API generation
system.

Change-Id: I2b574943008ed34696b048195c0cac6af1aa0a3b

api/current.txt

@@ -18706,7 +18706,6 @@ package android.os {
     method public final boolean hasFileDescriptors();
     method public final byte[] marshall();
     method public static android.os.Parcel obtain();
-    method protected static final android.os.Parcel obtain(int);
     method public final java.lang.Object[] readArray(java.lang.ClassLoader);
     method public final java.util.ArrayList readArrayList(java.lang.ClassLoader);
     method public final void readBinderArray(android.os.IBinder[]);

core/java/android/os/Parcel.java

@@ -2246,6 +2246,7 @@ public final class Parcel {
     private static final HashMap<ClassLoader,HashMap<String,Parcelable.Creator>>
         mCreators = new HashMap<ClassLoader,HashMap<String,Parcelable.Creator>>();
 
+    /** @hide for internal use only. */
     static protected final Parcel obtain(int obj) {
         final Parcel[] pool = sHolderPool;
         synchronized (pool) {