linuxulator: return EBADF for O_PATH mmap()

This fixes LTP open13, which expects O_PATH mmap() to fail with EBADF,
but FreeBSD returned EACCES.

PR:             295571

Signed-off-by: YAO, Xin <mr.yaoxin@outlook.com>

Author: ilovegrape

sys/compat/linux/linux_mmap.c

@@ -63,6 +63,10 @@ static int
 linux_mmap_check_fp(struct file *fp, int flags, int prot, int maxprot)
 {
 
+	/* Linux returns EBADF if mmap() is called on an O_PATH file descriptor */
+	if (fp->f_ops == &path_fileops)
+		return (EBADF);
+
 	/* Linux mmap() just fails for O_WRONLY files */
 	if ((fp->f_flag & FREAD) == 0)
 		return (EACCES);