Error No toolchains found in the NDK toolchains folder for ABI with prefix llvm

Question

I tried to use Gradel (gradlew clean build) to create an open source Android project (Netguard), but I ran into the following error:

A problem occurred configuring project ':app'.
> Exception thrown while executing model rule: NdkComponentModelPlugin.Rules#cre
ateToolchains
   > No toolchains found in the NDK toolchains folder for ABI with prefix: llvm

I searched but didn't find anything helping. Here is the main build.gradle:

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle-experimental:0.6.0-alpha1'
    }
}
allprojects {
    repositories {
        jcenter()
    }
}
task clean(type: Delete) {
    delete rootProject.buildDir
}

And here is the build.gradle of the app project:

apply plugin: 'com.android.model.application'

model {
    android {
        compileSdkVersion = 23
        buildToolsVersion = "23.0.2"

        defaultConfig.with {
            applicationId = "eu.faircode.netguard"
            minSdkVersion.apiLevel = 21
            targetSdkVersion.apiLevel = 23
            versionCode = 2016011801
            versionName = "0.76"
            archivesBaseName = "NetGuard-v$versionName-$versionCode"
        }
    }
    android.ndk {
        moduleName = "netguard"
        toolchain = "clang"
        ldLibs.add("log")
    }
    android.sources {
        main {
            jni {
                source {
                    srcDir "src/main/jni/netguard"
                }
                exportedHeaders {
                }
            }
        }
    }
    android.buildTypes {
        release {
            minifyEnabled = true
            proguardFiles.add(file('proguard-rules.pro'))
            ndk.with {
                debuggable = true
            }
        }
    }
    android.buildTypes {
        debug {
            ndk.with {
                debuggable = true
            }
        }
    }
    android.productFlavors {
        create("all") {
        }
    }
}

dependencies {


compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:23.1.+'
    compile 'com.android.support:recyclerview-v7:23.1.+'
    compile 'com.squareup.picasso:picasso:2.5.+'
}

Additionally, I'm running Android-NDK-R10e and Gradle-2.9-all. If you require any additional information, please comment because I'm not sure if I should say anything else.