Update generic signatures in codegen test data

The implementation of toString for generic types in Java reflection has
been changed in 8u162 (https://bugs.openjdk.java.net/browse/JDK-8054213)

compiler/testData/codegen/boxAgainstJava/sam/samConstructorGenericSignature.kt

@@ -18,6 +18,6 @@ import java.util.Arrays
 fun box(): String {
     val r: JavaClass.Computable<String> = JavaClass.Computable { "OK" }
     val supertypes = Arrays.toString(r.javaClass.getGenericInterfaces())
-    if (supertypes != "[JavaClass.JavaClass\$Computable<java.lang.String>]") return "Fail: $supertypes"
+    if (supertypes != "[JavaClass\$Computable<java.lang.String>]") return "Fail: $supertypes"
     return JavaClass.compute(r)!!
 }