Ignored/fixed some tests for Kotlin/Native

compiler/testData/codegen/box/when/enumOptimization/kt14597_full.kt

@@ -1,9 +1,5 @@
 enum class En { A, B, С }
 
-fun main(args: Array<String>) {
-
-}
-
 fun box(): String {
     var res1 = "fail"
     var res2 = "fail2"

compiler/testData/codegen/box/when/stringOptimization/sameHashCode.kt

@@ -1,5 +1,5 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
+// IGNORE_BACKEND: JS, NATIVE
 
 // WITH_RUNTIME