Introduce official public NativeWindow type.

Not yet hooked up to anything in the NDK, but requires renaming
the existing android_native_window_t type everywhere.

Change-Id: Iffee6ea39c93b8b34e20fb69e4d2c7c837e5ea2e
diff --git a/rsContext.cpp b/rsContext.cpp
index d8a9a99..596f533 100644
--- a/rsContext.cpp
+++ b/rsContext.cpp
@@ -473,7 +473,7 @@
     objDestroyOOBDestroy();
 }
 
-void Context::setSurface(uint32_t w, uint32_t h, android_native_window_t *sur)
+void Context::setSurface(uint32_t w, uint32_t h, ANativeWindow *sur)
 {
     rsAssert(mIsGraphicsContext);
 
@@ -888,7 +888,7 @@
     rsc->resume();
 }
 
-void rsi_ContextSetSurface(Context *rsc, uint32_t w, uint32_t h, android_native_window_t *sur)
+void rsi_ContextSetSurface(Context *rsc, uint32_t w, uint32_t h, ANativeWindow *sur)
 {
     rsc->setSurface(w, h, sur);
 }