port r14525 from 1.1: Also try to get struct timespec from unistd.h, at least some versions of mingw define it there

configure.ac

@@ -212,6 +212,7 @@ AC_CHECK_TYPES([struct timespec],
 	       [], [
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <unistd.h>
 #include <time.h>
 ])
 

include/pthread_win32/pthread.h

@@ -34,6 +34,7 @@ extern "C" {
 #include <windows.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <unistd.h>
 #include <time.h>
 #include <stdio.h>
 #include <errno.h>