fsnotify/fdinfo: include fdinfo.h for inotify_show_fdinfo()

inotify_show_fdinfo() is defined in fs/notify/fdinfo.c and declared in
fs/notify/fdinfo.h, but the declaration isn't included at the point of
the definition. Include the header to enforce that the definition
matches the declaration.

This addresses a gcc warning when -Wmissing-prototypes is enabled.

Signed-off-by: Eric Biggers <[e-mail]>
Signed-off-by: Jan Kara <[e-mail]>

fs/notify/fdinfo.c

···
 #include <linux/exportfs.h>
 
 #include "inotify/inotify.h"
+#include "fdinfo.h"
 #include "fsnotify.h"
 
 #if defined(CONFIG_PROC_FS)