Remove CRYPTO_TIMING.

It was added a very long time ago. It is single-threaded, so only
really useful for basic measurements, and in the meantime we've gotten
some more sophisticated profiling tools.

Reviewed by: cem, delphij, jhb
Sponsored by: Rubicon Communications, LLC (Netgate)
Differential Revision: https://reviews.freebsd.org/D25464

(cherry picked from commit a5c053f5a78ca68f9dcace37186142266787eaa0)