Do not define _POSIX_THREADS if unistd.h defines it.
Check for pthread_sigmask before using it. Fixes remaining problem in #470781.
M
Martin v. Löwis committed
69c0ff38362dff3b0a90828b8d787dfb3eb14bc3
Parent: c0f1bfe
Check for pthread_sigmask before using it. Fixes remaining problem in #470781.