systemclock: fix usage of __STDC_NO_ATOMICS__
__STDC_NO_ATOMICS
doesn't seem to exist. In fact the only compiler
I've found that sets any of those is msvc, but it sets
__STDC_NO_ATOMICS__
, not __STDC_NO_ATOMICS
.
__STDC_NO_ATOMICS__
is the one documented by C11 standard.
Edited by Alexander Slobodeniuk