io: drop nonnull attribute for fchmodat, faccessat, fchownat's path argument [BZ #34313]

Since Linux 6.11, AT_EMPTY_PATH can be used for a NULL path argument, so
the nonnull attribute is no longer sound. Drop it.

This bug was worked around in gnulib's 6db27b4dd36eda618db20e997ff56bbed7fce3cb.

See also 55618e1396 which fixed fstatat
in glibc.

Bug: https://sourceware.org/PR34313
Reviewed-by: Paul Eggert <eggert@cs.ucla.edu>

io/sys/stat.h

@@ -370,7 +370,7 @@ extern int fchmod (int __fd, __mode_t __mode) __THROW;
    the directory FD is open on.  */
 extern int fchmodat (int __fd, const char *__file, __mode_t __mode,
 		     int __flag)
-     __THROW __nonnull ((2)) __wur;
+     __THROW __wur;
 #endif /* Use ATFILE.  */
 
 

posix/unistd.h

@@ -307,7 +307,7 @@ extern int execveat (int __fd, const char *__path, char *const __argv[],
    If AT_EACCESS is set in FLAG, then use effective IDs like `eaccess',
    otherwise use real IDs like `access'.  */
 extern int faccessat (int __fd, const char *__file, int __type, int __flag)
-     __THROW __nonnull ((2)) __wur;
+     __THROW __wur;
 #endif /* Use GNU.  */
 
 
@@ -510,7 +510,7 @@ extern int lchown (const char *__file, __uid_t __owner, __gid_t __group)
    on.  */
 extern int fchownat (int __fd, const char *__file, __uid_t __owner,
 		     __gid_t __group, int __flag)
-     __THROW __nonnull ((2)) __wur;
+     __THROW __wur;
 #endif /* Use GNU.  */
 
 /* Change the process's working directory to PATH.  */