Make enum classes comparable

#KT-3727 Fixed

compiler/testData/diagnostics/tests/enum/overrideFinalEnumMethods.kt

@@ -4,6 +4,8 @@ enum class E {
     <!OVERRIDING_FINAL_MEMBER!>override<!> fun name(): String = "lol"
     <!OVERRIDING_FINAL_MEMBER!>override<!> fun ordinal(): Int = 0
 
+    <!OVERRIDING_FINAL_MEMBER!>override<!> fun compareTo(other: E) = -1
+
     <!OVERRIDING_FINAL_MEMBER!>override<!> fun equals(other: Any?) = true
     <!OVERRIDING_FINAL_MEMBER!>override<!> fun hashCode() = -1
 }