Here's a typical setup.
I don't know what's in your src/main/jni/Build.config
file, pretty sure it is not used or needed (please show it's contents).
.../app/build.gradle:
externalNativeBuild {
ndkBuild {
path 'src/main/jni/Android.mk'
}//ndkBuild
}//externalNativeBuild
.../app/src/main/jni/Application.mk:
#APP_ABI := armeabi armeabi-v7a x86 mips
APP_ABI := armeabi-v7a
APP_PLATFORM := android-19
APP_STL := stlport_static
#APP_OPTIM := debug
.../app/src/main/jni/Android.mk:
#=======================================================
LOCAL_PATH := $(call my-dir) #only call it ONCE !
#=======================================================
include $(CLEAR_VARS)
LOCAL_MODULE := hello_world
LOCAL_MULTILIB := 32
LOCAL_SRC_FILES := hello_world.cpp
include $(BUILD_SHARED_LIBRARY)
#-------------------------------------------------------
Links
android-gcc-toolchain