Native activity build with Android.mk fixed.

samples/android/native-activity/jni/Android.mk

@@ -6,7 +6,7 @@ include ../../sdk/native/jni/OpenCV.mk
 
 LOCAL_MODULE    := native_activity
 LOCAL_SRC_FILES := native.cpp
-LOCAL_LDLIBS    := -lm -llog -landroid
+LOCAL_LDLIBS    += -lm -llog -landroid
 LOCAL_STATIC_LIBRARIES := android_native_app_glue
 
 include $(BUILD_SHARED_LIBRARY)

samples/android/native-activity/jni/Application.mk

 APP_ABI := armeabi-v7a
+APP_STL := gnustl_static
+APP_CPPFLAGS := -frtti -fexceptions
 APP_PLATFORM := android-9