fs/attr.c: is_sxid can be boolean

This patch makes is_sxid return bool to improve readability
due to this particular function only using either one or zero
as its return value.

No functional change.
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/fs.h

@@ -2963,7 +2963,7 @@ int __init get_filesystem_list(char *buf);
 #define OPEN_FMODE(flag) ((__force fmode_t)(((flag + 1) & O_ACCMODE) | \
 					    (flag & __FMODE_NONOTIFY)))
 
-static inline int is_sxid(umode_t mode)
+static inline bool is_sxid(umode_t mode)
 {
 	return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
 }