Simple POSIX I/O emulation layer to work around Windows's defective

Unix I/O:
[_WIN32] (socklen_t, accept, posix_accept, bind. posix_bind, listen)
(posix_listen, setsockopt, posix_setsockopt, shutdown, posix_shutdown)
(socket, posix_socket, close, posix_close, creat, fstat, posix_fstat)
(lseek, posix_lseek, open, posix_open, read, posix_read, write)
(posix_write, fileno, posix_fileno, fcntl, O_NONBLOCK, F_RDLCK)
(F_WRLCK, F_GETFL, F_SETFL, F_SETLK, EWOULDBLOCK, ENOTSOCK)
(flock, fsync, posix_fsync):
New.
(ef_open, io_close, io_input, io_output, io_shutdown, io_noblocking)
(player_accept): Use them to simplify.
[_WIN32] (posix_fd2socket): New.
(empth_select): Use it.
(gen_power): Use it.

src/lib/commands/powe.c

@@ -35,11 +35,8 @@
  */
 
 #include <config.h>
-
+#include <unistd.h>
 #include <math.h>
-#ifdef _WIN32
-#include <io.h>
-#endif
 
 #include "commands.h"
 #include "item.h"
@@ -317,14 +314,13 @@ gen_power(struct powstr *powbuf, int save)
 	return;
     for (i = 0; i < MAXNOC; i++)
 	putpower(i, &powbuf[i]);
-#ifdef _WIN32
     /*
-     * At least some versions of Windows fail to update mtime on
-     * write().  Bad, because `power' displays that time.  Attempt to
-     * force an update.
+     * At least some versions of Windows fail to update st_mtime on
+     * write(), the st_mtime is not until the file is written to the
+     * disk.  Bad, because `power' displays that time.
+     * Force a sync to ensure the st_time is correct.
      */
-    _commit(empfile[EF_POWER].fd);
-#endif
+    fsync(empfile[EF_POWER].fd);
 }
 
 static int