lapi/fsmount.h: Include lapi/mount.h instead libc header

This allows us to get fallback definitions as well as including
<linux/mount.h> if presented, otherwise <sys/mount.h>.

Signed-off-by: Petr Vorel <pvorel@suse.cz>

include/lapi/fsmount.h

@@ -1,17 +1,18 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
+ * Copyright (c) Linux Test Project, 2021-2022
  * Copyright (c) 2020 Linaro Limited. All rights reserved.
  * Author: Viresh Kumar <viresh.kumar@linaro.org>
  */
 
 #ifndef LAPI_FSMOUNT_H__
 #define LAPI_FSMOUNT_H__
 
-#include <sys/mount.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
 
 #include "config.h"
+#include "lapi/mount.h"
 #include "lapi/fcntl.h"
 #include "lapi/syscalls.h"