JVM: enable -Xlambdas=class for some backend tests

These tests are checking the specifics of the class-generated lambdas.

compiler/testData/checkLocalVariablesTable/destructuringInLambdas.kt

@@ -1,3 +1,5 @@
+// LAMBDAS: CLASS
+
 data class A(val x: String, val y: Int)
 
 fun foo(a: A, block: (A) -> String): String = block(a)

compiler/testData/checkLocalVariablesTable/itInLambda.kt

@@ -1,3 +1,5 @@
+// LAMBDAS: CLASS
+
 public fun <T> Iterable<T>.myforEach(operation: (T) -> Unit) : Unit {
     for (element in this) operation(element)
 }

compiler/testData/checkLocalVariablesTable/itInReturnedLambda.kt

@@ -1,3 +1,5 @@
+// LAMBDAS: CLASS
+
 fun foo() {
     fun bar() : (Int) -> Unit {
         return {

compiler/testData/checkLocalVariablesTable/lambdaAsVar.kt

@@ -1,3 +1,5 @@
+// LAMBDAS: CLASS
+
 fun foo() {
     var a = {
 

compiler/testData/checkLocalVariablesTable/objectInLocalPropertyDelegate.kt

@@ -1,3 +1,5 @@
+// LAMBDAS: CLASS
+
 operator fun (() -> String).getValue(thisRef: Any?, property: Any?) = this()
 
 fun foo() {

compiler/testData/checkLocalVariablesTable/underscoreNames.kt

@@ -1,3 +1,5 @@
+// LAMBDAS: CLASS
+
 data class A(val x: Double = 1.0, val y: String = "", val z: Char = '0')
 
 fun foo(a: A, block: (A, String, Int) -> String): String = block(a, "", 1)