gcc-10 warnings: fix low-hanging fruit

Backport of 9d82973

Original description below
---

Due to a bug-report that was compiler-dependent, I updated one of my
machines to gcc-10.  That shows a lot of new warnings.  Happily they
seem to be mostly the valid kind, but it's going to cause a round of
churn for getting rid of them..

This is the really low-hanging fruit of removing a couple of zero-sized
arrays in some core code.  We have had a round of these patches before,
and we'll have many more coming, and there is nothing special about
these except that they were particularly trivial, and triggered more
warnings than most.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: torvalds

include/linux/fs.h

@@ -938,7 +938,7 @@ struct file_handle {
 	__u32 handle_bytes;
 	int handle_type;
 	/* file identifier */
-	unsigned char f_handle[0];
+	unsigned char f_handle[];
 };
 
 static inline struct file *get_file(struct file *f)

include/linux/tty.h

@@ -64,7 +64,7 @@ struct tty_buffer {
 	int read;
 	int flags;
 	/* Data points here */
-	unsigned long data[0];
+	unsigned long data[];
 };
 
 /* Values for .flags field of tty_buffer */