constify JNINativeMethod function pointer tables

Change-Id: I4036c924958221cbc644724f8eb01c5de3cd7954
diff --git a/core/jni/android_os_Debug.cpp b/core/jni/android_os_Debug.cpp
index 1d2a7d9..0701700 100644
--- a/core/jni/android_os_Debug.cpp
+++ b/core/jni/android_os_Debug.cpp
@@ -946,7 +946,7 @@
  * JNI registration.
  */
 
-static JNINativeMethod gMethods[] = {
+static const JNINativeMethod gMethods[] = {
     { "getNativeHeapSize",      "()J",
             (void*) android_os_Debug_getNativeHeapSize },
     { "getNativeHeapAllocatedSize", "()J",