conc059 fails on Darwin
Compile failed (exit code 1) errors were:
conc059_c.c:40:19: error:
error: implicit declaration of function 'nanosleep' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
int ret = nanosleep(&ts, &ts);
^
1 error generated.
`clang' failed in phase `C Compiler'. (Exit code: 1)
*** unexpected failure for conc059(threaded1)
Visible in https://gitlab.haskell.org/ghc/ghc/-/jobs/596291, https://gitlab.haskell.org/ghc/ghc/-/jobs/596648