Replace ndk.dir with ndkPath.

https://developer.android.com/studio/projects/configure-agp-ndk#agp_version_41

The documentation tells you to be careful about this, since you're
putting local-only information into a file that gets uploaded to version
control, but Lime doesn't really need to worry about that.

Granted, Lime DID use local.properties, but that's no longer practical.

templates/android/template/app/build.gradle

@@ -10,6 +10,7 @@ System.setProperty('java.awt.headless','false')
 android {
 	compileSdkVersion Integer.parseInt(project.ANDROID_BUILD_SDK_VERSION)
 	buildToolsVersion project.ANDROID_BUILD_TOOLS_VERSION
+	::if (ANDROID_GRADLE_PLUGIN>="4.0")::ndkPath '::ANDROID_NDK_ROOT_ESCAPED::'::end::
 	
 	defaultConfig {
 		applicationId "::META_PACKAGE_NAME::"

templates/android/template/build.gradle

@@ -46,6 +46,7 @@ configure(subprojects.findAll {!it.file('build.gradle').exists() && it.file('bui
 	android {
 		compileSdkVersion Integer.parseInt(project.ANDROID_BUILD_SDK_VERSION)
 		buildToolsVersion project.ANDROID_BUILD_TOOLS_VERSION
+		::if (ANDROID_GRADLE_PLUGIN>="4.0")::ndkPath '::ANDROID_NDK_ROOT_ESCAPED::'::end::
 		
 		sourceSets {
 			main {

templates/android/template/local.properties

@@ -4,4 +4,6 @@
 # Location of the SDK. This is only used by Gradle.
 #
 sdk.dir=::ANDROID_SDK_ESCAPED::
+::if (ANDROID_GRADLE_PLUGIN<"4.0")::
 ndk.dir=::ANDROID_NDK_ROOT_ESCAPED::
+::end::