Disable nebula.lint plugin pending a bug fix

This plugin provides a "lintGradle" task that checks for certain common
Gradle mistakes.  However, the 14.x version we had been using triggers
eager configuration of many Java-related tasks.  More recent 16.x
releases fix that, but we cannot use those due to a known nebula.lint
bug.

I cannot remember the last time this linter actually found any problems.
So let's disable it entirely for now.  We can bring it back once we can
upgrade it to a 16.x+ release.

build.gradle

@@ -13,7 +13,7 @@ plugins {
 	id 'com.github.sherter.google-java-format' version '0.8'
 	id 'de.set.ecj' version '1.4.1' apply false
 	id 'de.undercouch.download'
-	id 'nebula.lint' version '14.2.5'
+//	id 'nebula.lint' version '14.2.5'
 }
 
 repositories {
@@ -185,6 +185,8 @@ tasks.register('aggregatedJavadocs', Javadoc) {
 //
 
 // Gradle build scripts
+// disabled until <https://github.com/gradle/gradle/issues/6246> is fixed
+/*
 allprojects {
 	apply plugin: 'nebula.lint'
 	gradleLint.alwaysRun = false
@@ -197,6 +199,7 @@ allprojects {
 		]
 	}
 }
+*/
 
 // shell scripts, provided they have ".sh" extension
 if (isWindows) {
@@ -249,7 +252,7 @@ tasks.register('installGitHooks', Copy) {
 tasks.register('linters') {
 	group = 'lint'
 	dependsOn(
-			'lintGradle',
+			// 'lintGradle',
 			'shellCheck',
 	)
 	if (!(isWindows && System.getenv('GITHUB_ACTIONS') == 'true')) {