f2857af485
Testing on CI showed that Cygwin's semctl() can fail with EAGAIN (possibly due to resource limits in cygserver that could be tuned, not examined). Switch to so-called POSIX semaphores instead, which don't seem to fail in that way (possibly due to a more direct implementation using Windows semaphore primitives instead of talking to cygserver, based on a cursory glance at the source). Other known problems still prevent PostgreSQL from running on Cygwin without random crashes, but this rarer problem was noticed while testing. Discussion: https://postgr.es/m/CA%2BhUKG%2BQ6DU4Ov9LrvUyDcF3oHS4KMRVSKmVGaeePq-kOyG9gA%40mail.gmail.com