Do not set api version to language version when language version is null

#KT-21852 fixed
    #KT-21574 fixed

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/argumentUtils.kt

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.cli.common.arguments
 
+import com.intellij.util.text.VersionComparatorUtil
 import java.util.*
 import kotlin.reflect.KClass
 import kotlin.reflect.KMutableProperty1
@@ -98,4 +99,10 @@ fun <T : Any> collectProperties(kClass: KClass<T>, inheritedOnly: Boolean): List
     return properties.filter {
         it.visibility == KVisibility.PUBLIC && it.findAnnotation<Transient>() == null
     }
+}
+
+fun CommonCompilerArguments.setApiVersionToLanguageVersionIfNeeded() {
+    if (languageVersion != null && VersionComparatorUtil.compare(languageVersion, apiVersion) < 0) {
+        apiVersion = languageVersion
+    }
 }