Update build options

Drop unnecessary cleanLibs task, fix link to LICENSE file, set encoding
to UTF-8.

Author: damianmalczewski

buildSrc/src/main/kotlin/internal.common-convention.gradle.kts

@@ -8,16 +8,6 @@ repositories {
     mavenCentral()
 }
 
-// Utility to clean up old jars as they can clutter.
-// Usage:
-//   ./gradlew cleanLibs
-tasks.register<Delete>("cleanLibs") {
-    description = "Deletes build/libs directory."
-    group = "build"
-
-    delete(layout.buildDirectory.dir("libs"))
-}
-
 // Usage:
 //   ./gradlew printVersion
 tasks.register<DefaultTask>("printVersion") {

buildSrc/src/main/kotlin/internal.java-library-convention.gradle.kts

@@ -13,17 +13,17 @@ java {
 
 tasks.withType<JavaCompile>().configureEach {
     options.compilerArgs.add("-parameters")
+    options.encoding = "UTF-8"
 }
 
 tasks.withType<Jar>().configureEach {
-    dependsOn("cleanLibs")
     manifest {
         attributes["Implementation-Title"] = project.name
         attributes["Implementation-Version"] = project.version
         attributes["Build-Jdk-Spec"] = java.toolchain.languageVersion.get().toString()
         attributes["Created-By"] = "Gradle ${gradle.gradleVersion}"
     }
-    from("LICENSE") {
+    from("${rootProject.rootDir}/LICENSE") {
         into("META-INF/")
         rename { "LICENSE.txt" }
     }