hideif.el: Minor cleanup

hideif.el: Minor cleanup

* lisp/progmodes/hideif.el: Prefer #' to quote function names.
(hif-eval): Use `lexical-binding`.
(hif-ifx-regexp): Don't use `defconst` since `bovine/c.el` let-binds it.
(hif--intern-safe): Rename from `intern-safe` to fix this
namespace violation.
(hif-strtok): Adjust accordingly.