Use build.gradle to compile all jars in libs folder and ndk support

build.gradle

//compile all jar in libs folder
dependencies {
    compile fileTree(dir: 'libs' , include: '*.jar')
}
//pack all so file into a jar and compile it
task nativeLibsToJar(
        type: Zip,
        description: 'create a jar archive of the native libs') {
    destinationDir file('./libs')
    baseName 'native-libs'
    extension 'jar'

    from 'libs'
    include '**/*.so'
    into 'lib'
}

tasks.withType(Compile) {
    compileTask -> compileTask.dependsOn(nativeLibsToJar)
}

clean.dependsOn 'cleanNativeLibsToJar'