mie: add strict-naming support to mie_name_map

in strict mode, the hint is taken as the required name. if a value already
exists with the given name, the operation fails.

mie/name.c

@@ -123,7 +123,8 @@ static b_status put_name(struct mie_name_map *map, struct mie_name *name)
 }
 
 struct mie_name *mie_name_map_put(
-	struct mie_name_map *map, struct mie_name *entry, const char *hint)
+	struct mie_name_map *map, struct mie_name *entry, const char *hint,
+	enum mie_name_map_flags flags)
 {
 	memset(entry, 0x0, sizeof *entry);
 	entry->n_base.e_type = MIE_NAME_MAP_E_NAME;
@@ -149,6 +150,12 @@ struct mie_name *mie_name_map_put(
 		}
 	}
 
+	if (flags & MIE_NAME_MAP_STRICT) {
+		/* the caller insists that `hint` be used as the name.
+		 * such a name already exists, so we can't help them */
+		return NULL;
+	}
+
 	/* that name already exists, use a suffix to make the name unique.
 	 * alternately, no hint was specified, so it's up to us to generate the name */
 	b_rope dot = B_ROPE_CHAR('.');