ima: Replace zero-length array with flexible-array

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

security/integrity/integrity.h

@@ -107,7 +107,7 @@ struct ima_digest_data {
 		} ng;
 		u8 data[2];
 	} xattr;
-	u8 digest[0];
+	u8 digest[];
 } __packed;
 
 /*
@@ -119,7 +119,7 @@ struct signature_v2_hdr {
 	uint8_t	hash_algo;	/* Digest algorithm [enum hash_algo] */
 	__be32 keyid;		/* IMA key identifier - not X509/PGP specific */
 	__be16 sig_size;	/* signature size */
-	uint8_t sig[0];		/* signature payload */
+	uint8_t sig[];		/* signature payload */
 } __packed;
 
 /* integrity data associated with an inode */