Retire LOCAL_NDK_VERSION.

Bug: 6932421
Change-Id: Iee6285681aa85f57cf70fd4846bd2e01ef1b67c9
diff --git a/ndk/platforms/android-9/samples/native-activity/Android.mk b/ndk/platforms/android-9/samples/native-activity/Android.mk
index 73b3d87..a092f41 100644
--- a/ndk/platforms/android-9/samples/native-activity/Android.mk
+++ b/ndk/platforms/android-9/samples/native-activity/Android.mk
@@ -39,7 +39,6 @@
 	jni/main.c \
 	../../../../sources/android/native_app_glue/android_native_app_glue.c
 
-LOCAL_NDK_VERSION := 4
 LOCAL_SDK_VERSION := 8
 
 LOCAL_SHARED_LIBRARIES := liblog libandroid libEGL libGLESv1_CM