simple speed check macro

[Paul Pogonyshev]

Not sure if Emacs has something similar already, at least I
couldn't find it.

(defmacro measure-time-spent (&rest body)
  (declare (indent 0) (debug t))
  `(let ((start-time  (prog1 (current-time)
                        ,@body))
         (finish-time (current-time)))
     (+ (* (- (nth 2 finish-time) (nth 2 start-time)) 1e-6)
           (- (nth 1 finish-time) (nth 1 start-time))
        (* (- (nth 0 finish-time) (nth 0 start-time)) #x10000))))

It can be used for quick speed checks like this:

        M-: (measure-time-spent (foo) (bar))

Does this look useful enough for a patch?

Paul