fix int vs. pointer mismatch in return statement.
Add missing include header for compilation on x86 target.

Change-Id: I3651fb3be0178b888c5ada3d3754fb379b55a847
diff --git a/core/jni/android_util_AssetManager.cpp b/core/jni/android_util_AssetManager.cpp
index c4056a4..2528db1 100644
--- a/core/jni/android_util_AssetManager.cpp
+++ b/core/jni/android_util_AssetManager.cpp
@@ -1296,7 +1296,7 @@
 {
     AssetManager* am = assetManagerForJavaObject(env, clazz);
     if (am == NULL) {
-        return NULL;
+        return 0;
     }
     const ResTable& res(am->getResources());