suppress EINTR in sem_wait and sem_timedwait
suppress EINTR in sem_wait and sem_timedwait

per POSIX, the EINTR condition is an optional error for these
functions, not a mandatory one. since old kernels (pre-2.6.22) failed
to honor SA_RESTART for the futex syscall, it's dangerous to trust
EINTR from the kernel. thankfully POSIX offers an easy way out.

chardi/musl,chardi/musl,chardi/musl