workaround CCL optimization bug for digests
workaround CCL optimization bug for digests

Anything higher than (SPEED 0) causes mysterious test failures; this
declaration doesn't seem to affect the speed much in any event.  Tested
with CCL Linux/x86-64; it's possible the bug appears in older versions
as well.

glv2/ironclad,sharplispers/ironclad,eadmund/ironclad,froydnj/ironclad