[FE 1.0] Fix remaining codegen spec tests

compiler/tests-spec/testData/codegen/box/linked/expressions/when-expression/p-4/neg/1.2.exceptions.compiletime.txt

@@ -1 +1 @@
-java.lang.IllegalStateException: NO_ELSE_IN_WHEN: 'when' expression must be exhaustive, add necessary 'false' branch or 'else' branch instead (15,17) in /1.2.kt
+java.lang.IllegalStateException: NO_ELSE_IN_WHEN: 'when' expression must be exhaustive, add necessary 'true', 'false' branches or 'else' branch instead (15,17) in /1.2.kt

compiler/tests-spec/testData/codegen/box/linked/expressions/when-expression/p-4/pos/1.2.kt

@@ -15,6 +15,7 @@ fun box(): String {
         false -> { "NOK" }
         !false -> { "OK" }
         !false -> { "NOK" }
+        else -> { "NOK" }
     }
     return  when2
-}
+}