partition/makefs: Include missing sys/file.h header

This file must be included on non-glibc systems to ensure
the `LOCK_EX` definition is available.

Signed-off-by: Ikey Doherty <ikey.doherty@lispysnake.com>

src/partition/makefs.c

@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
 #include <fcntl.h>
+#include <sys/file.h>
 #include <sys/prctl.h>
 #include <sys/stat.h>
 #include <sys/types.h>