Check availability of linux/magic.h. It isn't available in Linux
versions before 2.6.19.
AC_CHECK_HEADERS([sys/vfs.h sys/mount.h sys/vmount.h sys/statfs.h sys/statvfs.h])
AC_CHECK_HEADERS([mntent.h sys/mnttab.h sys/vfstab.h sys/mntctl.h sys/sysctl.h fstab.h])
AC_CHECK_HEADERS([sys/uio.h sys/mkdev.h])
+AC_CHECK_HEADERS([linux/magic.h])
# check for structure fields
AC_CHECK_MEMBERS([struct stat.st_mtimensec, struct stat.st_mtim.tv_nsec, struct stat.st_atimensec, struct stat.st_atim.tv_nsec, struct stat.st_ctimensec, struct stat.st_ctim.tv_nsec])
#include "gstdio.h"
#include "glibintl.h"
-#ifdef __linux__ /* for btrfs check */
+#ifdef HAVE_LINUX_MAGIC_H /* for btrfs check */
#include <linux/magic.h>
#include <sys/vfs.h>
#endif