Some native activity sample code cleanup.

Update to include newest headers and library, tweak glue code to
work better with state saving and add support for config changes.

Change-Id: I4d27bd4a0f542f217efaec86cf4f219aca020426

ndk/platforms/android-9/samples/native-activity/src/Dummy.java

@@ -0,0 +1,4 @@
+// Temporary until the NDK build system can deal with there being no Java source.
+class Dummy {
+
+}