pass AT_NO_AUTOMOUNT when emulating fstatat via statx

AT_NO_AUTOMOUNT is implied for stat/lstat/fstatat syscalls since Linux
3.1 (commit b6c8069d3577481390b3f24a8434ad72a3235594). However, this
is not the case for statx syscall, which defaults to automounting, so
this flag must be passed explicitly when statx is used to implement
stat-like functions.

This change affects only arches which use 32-bit seconds in struct kstat,
as well as out-of-tree/future ports to arches which lack SYS_fstatat.

src/stat/fstatat.c

@@ -36,6 +36,7 @@ static int fstatat_statx(int fd, const char *restrict path, struct stat *restric
 {
 	struct statx stx;
 
+	flag |= AT_NO_AUTOMOUNT;
 	int ret = __syscall(SYS_statx, fd, path, flag, 0x7ff, &stx);
 	if (ret) return ret;