The attached patch adds a :enum clause to sb-grovel. Using it causes
extraction of the enumeration constants and the definition of an alien
enum type using these constants.
(You can of course use this for enumerations defined using C
preprocessor constants and C enums alike. It's especially useful for
the C enums though, as the current sb-grovel :integer clauses can't
be used for these because the printf statements that extract them
are surrounded by #ifdef/#endif.)