SI-8960 Bring back the SerialVersionUID to anonymous function classes

In PR #1673 / 4267444, the annotation `SerialVersionId` was changed
from a `StaticAnnotation` to `ClassFileAnnotation` in order to enforce
annotation arguments to be constants. That was 2.11.0.

The ID value in the AnnotationInfo moved from `args` to `assocs`, but
the backend was not adjusted. This was fixed in PR #3711 / ecbc9d0 for
2.11.1.

Unfortunately, the synthetic AnnotationInfo that is added to anonymous
function classes still used the old constructor (`args` instead of
`assocs`), so extracting the value failed, and no field was added to
the classfile.
Merge pull request #4093 from lrytz/t8960

SI-8960 Bring back the SerialVersionUID to anonymous function classes