libfuse cleanup: add more header include guards

libfuse/lib/fuse_i.h

@@ -6,6 +6,8 @@
   See the file COPYING.LIB
 */
 
+#pragma once
+
 #include "fuse.h"
 #include "fuse_lowlevel.h"
 

libfuse/lib/fuse_misc.h

@@ -6,7 +6,10 @@
   See the file COPYING.LIB
 */
 
+#pragma once
+
 #include "config.h"
+
 #include <pthread.h>
 
 /*

libfuse/lib/mount_util.h

@@ -6,6 +6,8 @@
   See the file COPYING.LIB.
 */
 
+#pragma once
+
 #include <sys/types.h>
 
 int fuse_mnt_add_mount(const char *progname, const char *fsname,