ssb: Make blocks begin to do something.

src/ssb.db.h

@@ -631,4 +631,12 @@ void tf_ssb_db_add_block(sqlite3* db, const char* id);
 */
 void tf_ssb_db_remove_block(sqlite3* db, const char* id);
 
+/**
+** Check if an ID is blocked on this instance.
+** @param db The database.
+** @param id The account, message, or blob ID to check.
+** @return true if the id is blocked.
+*/
+bool tf_ssb_db_is_blocked(sqlite3* db, const char* id);
+
 /** @} */