These standard functions are much more powerful than the C random()
routines. Use them to improve the random utils, and use a class
to clean things up further.

This fixes a problem I was having using random_utils where I was
having trouble generating random 32 bit unsigned integers.

BUG=angleproject:1290

Change-Id: I5081764053d0667a4e323553b7dea531256aa778
Reviewed-on: https://chromium-review.googlesource.com/323440Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>