Set thread context classloader in the kotlin runner

#KT-26624 fixed

compiler/cli/cli-runner/src/org/jetbrains/kotlin/runner/runners.kt

@@ -57,6 +57,8 @@ abstract class AbstractRunner : Runner {
             )
         }
 
+        Thread.currentThread().contextClassLoader = classLoader
+
         try {
             main.invoke(null, arguments.toTypedArray())
         }

compiler/testData/launcher/contextClassLoaderTester.kt

@@ -0,0 +1,11 @@
+
+object ContextClassLoaderTester {
+
+    @JvmStatic
+    fun main(args: Array<String>) {
+        kotlin.test.DefaultAsserter.assertTrue("", true) // this tests that kotlin-test is in the compilation and runtime classpaths
+        val contextClassLoader = Thread.currentThread().getContextClassLoader()
+        contextClassLoader.loadClass("kotlin.test.DefaultAsserter") // this tests that thread context classloader is set correctly
+        println("ok")
+    }
+}

compiler/tests/org/jetbrains/kotlin/cli/LauncherScriptTest.kt

@@ -88,6 +88,24 @@ class LauncherScriptTest : TestCaseWithTmpdir() {
         )
     }
 
+    fun testKotlinJvmContextClassLoader() {
+        val kotlinTestJar = File(PathUtil.kotlinPathsForDistDirectory.homePath, "lib/kotlin-test.jar")
+        assertTrue("kotlin-main-kts.jar not found, run dist task: ${kotlinTestJar.absolutePath}", kotlinTestJar.exists())
+        runProcess(
+            "kotlinc",
+            "-cp", kotlinTestJar.path,
+            "$testDataDirectory/contextClassLoaderTester.kt",
+            "-d", tmpdir.path
+        )
+
+        runProcess(
+            "kotlin",
+            "-cp", listOf(tmpdir.path, kotlinTestJar.path).joinToString(File.pathSeparator),
+            "ContextClassLoaderTester",
+            expectedStdout = "ok\n"
+        )
+    }
+
     fun testKotlincJsSimple() {
         runProcess(
                 "kotlinc-js",