unix: add fs-verity consts and types

See https://www.kernel.org/doc/html/latest/filesystems/fsverity.html for
details.

Change-Id: I5b02d0ef84f21d05ea3f1ac8e905232733ea3739
Reviewed-on: https://go-review.googlesource.com/c/sys/+/225698
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/mkerrors.sh

@@ -200,6 +200,7 @@ struct ltchars {
 #include <linux/filter.h>
 #include <linux/fs.h>
 #include <linux/fscrypt.h>
+#include <linux/fsverity.h>
 #include <linux/genetlink.h>
 #include <linux/hdreg.h>
 #include <linux/icmpv6.h>
@@ -506,7 +507,8 @@ ccflags="$@"
 		$2 ~ /^CAP_/ ||
 		$2 ~ /^ALG_/ ||
 		$2 ~ /^FS_(POLICY_FLAGS|KEY_DESC|ENCRYPTION_MODE|[A-Z0-9_]+_KEY_SIZE)/ ||
-		$2 ~ /^FS_IOC_.*ENCRYPTION/ ||
+		$2 ~ /^FS_IOC_.*(ENCRYPTION|VERITY|GETFLAGS)/ ||
+		$2 ~ /^FS_VERITY_/ ||
 		$2 ~ /^FSCRYPT_/ ||
 		$2 ~ /^GRND_/ ||
 		$2 ~ /^RND/ ||