SI-7159 Remove erroneous INT <:< LONG in TypeKinds

TypeKinds said INT <:< LONG. But that's not true on the JVM, you need
a coercion to move up. And GenICode#adapt was checking for just that
special case.

This commit removes the INT <:< LONG rule and then removes the special
case from GenICode#adapt.

A test is included that reproduces the problem reported in SI-107, the
bug that created the need for the special case in GenICode#adapt.