Migrate repo to use JVM toolchains Gradle feature.

^KT-46972 Fixed

libraries/stdlib/jvm/build.gradle

@@ -4,7 +4,9 @@ apply plugin: 'kotlin-platform-jvm'
 
 archivesBaseName = 'kotlin-stdlib'
 
-configureJvm6Project(project)
+JvmToolchain.configureJvmToolchain(project, JdkMajorVersion.JDK_1_6)
+LibrariesCommon.disableDeprecatedJvmTargetWarning(project)
+
 configurePublishing(project)
 configureJavadocJar()
 configureSourcesJar()
@@ -38,6 +40,8 @@ sourceSets {
     }
 }
 
+LibrariesCommon.configureJava9Compilation(project, 'kotlin.stdlib', [sourceSets.main.output])
+
 configurations {
     commonSources
     longRunningTestCompile.extendsFrom(testCompile)
@@ -127,9 +131,6 @@ compileKotlin {
     }
 }
 
-
-compileJava9Sources(project, 'kotlin.stdlib', [sourceSets.main.output])
-
 compileTestKotlin {
     kotlinOptions {
         freeCompilerArgs += [