libctf: create, types: enums and enum64s; type encoding

libctf: create, types: enums and enum64s; type encoding

This commit adapts most aspects of enum handling: querying and iteration,
enumerator querying and iteration, ctf_type_add, etc.  We have to adapt to
enum64s and to signed versus unsigned enums, to our vlen and DTD changes and
other internal API changes to handle prefix types etc, and fix the types of
things to allow for 64-bit enumerators.  We can also (finally!) get useful
info on enum size rather than being restricted to a value hardwired into
libctf.

We also adjust all the type-encoding functions for the internal API changes,
since enums are the first encodable entities we have covered.

API changes:

-typedef int ctf_enum_f (const char *name, int val, void *arg);
+typedef int ctf_enum_f (const char *name, int64_t val, void *arg);
+typedef int ctf_unsigned_enum_f (const char *name, uint64_t val, void *arg);

-extern const char *ctf_enum_name (ctf_dict_t *, ctf_id_t, int);
-extern int ctf_enum_value (ctf_dict_t *, ctf_id_t, const char *, int *);
+extern const char *ctf_enum_name (ctf_dict_t *, ctf_id_t, int64_t);
+extern int ctf_enum_value (ctf_dict_t *, ctf_id_t, const char *, int64_t *);
+extern int ctf_enum_unsigned_value (ctf_dict_t *, ctf_id_t, const char *, uint64_t *);
+
+/* Return 1 if this enum's contents are unsigned, so you can tell which of the
+   above functions to use.  */
+
+extern int ctf_enum_unsigned (ctf_dict_t *, ctf_id_t);

-/* Return all enumeration constants in a given enum type.  */
-extern int ctf_enum_iter (ctf_dict_t *, ctf_id_t, ctf_enum_f *, void *);
+/* Return all enumeration constants in a given enum type.  The return value, and
+   VAL argument, may need to be cast to uint64_t: see ctf_enum_unsigned().  */
+extern int64_t ctf_enum_iter (ctf_dict_t *, ctf_id_t, ctf_enum_f *, void *);
 extern const char *ctf_enum_next (ctf_dict_t *, ctf_id_t, ctf_next_t **,
-				  int *);
+				  int64_t *);
+
+/* enums are created signed by default.  If you want an unsigned enum,
+   use ctf_add_enum_encoded() with an encoding of 0 (CTF_INT_SIGNED and
+   everything else off).  This will not create a slice, unlike all other
+   uses of ctf_add_enum_encoded(), and the result is still representable
+   as BTF.  */
+
+extern ctf_id_t ctf_add_enum64_encoded (ctf_dict_t *, uint32_t, const char *,
+					const ctf_encoding_t *);
+extern ctf_id_t ctf_add_enum64 (ctf_dict_t *, uint32_t, const char *);

-extern int ctf_add_enumerator (ctf_dict_t *, ctf_id_t, const char *, int);
+extern int ctf_add_enumerator (ctf_dict_t *, ctf_id_t, const char *, int64_t);

The only aspects of enums that are not now handled are forwards to enums,
dumping of enums, and deduplication of enums.