autofs: include limit.h before auto_fs.h

In file included from /home/travis/build/xemul/criu/criu/include/autofs.h:16:0,
                 from autofs.c:7:
/usr/include/linux/auto_fs.h:54:12: error: ‘NAME_MAX’ undeclared here (not in a function)
  char name[NAME_MAX+1];

In file included from /home/travis/build/xemul/criu/criu/include/autofs.h:16:0,
                 from autofs.c:7:
/usr/include/linux/auto_fs.h:54:12: error: ‘NAME_MAX’ undeclared here (not in a function)
  char name[NAME_MAX+1];
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/include/autofs.h

@@ -13,6 +13,7 @@ int autofs_dump(struct mount_info *pm);
 int autofs_mount(struct mount_info *mi, const char *source, const
 		 char *filesystemtype, unsigned long mountflags);
 
+#include <linux/limits.h>
 #include <linux/auto_fs.h>
 
 #include <string.h>