message: Use anonymous fmap
diff: @@ -739,19 +739,7 @@ impl Pal for Sys {
  };
  if flags & MAP_ANONYMOUS == MAP_ANONYMOUS {
  - let fd = e(syscall::open(
  - "memory:",
  - syscall::O_STAT | syscall::O_CLOEXEC,
  - )); // flags don't matter currently
  - if fd == !0 {
  - return !0 as *mut c_void;
  - }
  -
  - let addr = e(syscall::fmap(fd, &map)) as *mut c_void;
  -
  - let _ = syscall::close(fd);
  -
  - addr
  + e(syscall::fmap(!0, &map)) as *mut c_void
  } else {
  e(syscall::fmap(fildes as usize, &map)) as *mut c_void
  }
  