Set "$USE_DEPRECATED_NDK=true" in gradle.properties to continue using the current NDK integration. 解

一、将 jni 文件夹名改成 cpp；

二、添加 CMakeLists.txt;

三、修改 build.gradle;

    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }

【参考】

https://developer.android.com/studio/projects/add-native-code.html