https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62024
--- Comment #4 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- Whatever we do for __atomic_always_lock_free, note that we'll probably need to find some way for ATOMIC_*_LOCK_FREE (in stdatomic.h) to expand to something usable in #if. http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_458.htm
