Minor, move ContentRoot and KotlinSourceRoot to module 'cli'

Also move CONTENT_ROOTS from JVMConfigurationKeys to
CLIConfigurationKeys since it's used on all platforms, not just JVM

compiler/frontend.java/src/org/jetbrains/kotlin/config/ContentRoots.kt

@@ -1,31 +0,0 @@
-/*
- * Copyright 2010-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.kotlin.config
-
-interface ContentRoot
-
-data class KotlinSourceRoot(val path: String): ContentRoot
-
-fun CompilerConfiguration.addKotlinSourceRoot(source: String) {
-    add(JVMConfigurationKeys.CONTENT_ROOTS, KotlinSourceRoot(source))
-}
-
-fun CompilerConfiguration.addKotlinSourceRoots(sources: List<String>): Unit =
-        sources.forEach(this::addKotlinSourceRoot)
-
-val CompilerConfiguration.kotlinSourceRoots: List<String>
-    get() = get(JVMConfigurationKeys.CONTENT_ROOTS)?.filterIsInstance<KotlinSourceRoot>()?.map { it.path }.orEmpty()

compiler/frontend.java/src/org/jetbrains/kotlin/config/JVMConfigurationKeys.java

@@ -30,10 +30,6 @@ public class JVMConfigurationKeys {
     private JVMConfigurationKeys() {
     }
 
-    // roots, including dependencies and own source
-    public static final CompilerConfigurationKey<List<ContentRoot>> CONTENT_ROOTS =
-            CompilerConfigurationKey.create("content roots");
-
     public static final CompilerConfigurationKey<File> OUTPUT_DIRECTORY =
             CompilerConfigurationKey.create("output directory");
     public static final CompilerConfigurationKey<File> OUTPUT_JAR =