Do not autoload defcustoms in hippie-exp.el

Do not autoload defcustoms in hippie-exp.el

* lisp/hippie-exp.el (hippie-expand-try-functions-list)
(hippie-expand-verbose, hippie-expand-dabbrev-skip-space)
(hippie-expand-dabbrev-as-symbol, hippie-expand-no-restriction)
(hippie-expand-max-buffers, hippie-expand-ignore-buffers)
(hippie-expand-only-buffers): Do not autoload defcustoms.
* lisp/progmodes/vhdl-mode.el (vhdl-line-expand):
Explicitly load hippie-exp, so it does not get autoloaded
while hippie-expand-try-functions-list is let-bound.