`*xattrat` syscalls

[rusty-snake]

Linux 6.13 added *at variants of xattr syscalls:

• struct xattr_args
• setxattrat
• getxattrat
• listxattrat
• removexattrat

struct xattr_args { value, size, flags };
setxattrat(dfd: c_int, pathname: *const c_char, at_flags: c_uint, name: *const c_char, args: *const xattr_args, size: c_size_t);
getxattrat(dfd: c_int, path: *const c_char, at_flags: c_uint, name: *const c_char, args: *const xattr_args, size: c_size_t);
listxattrat(dfd: c_int, path: *const c_char, at_flags: c_uint, list: *mut c_char, size: c_size_t);
removexattrat(dfd: int, path: *const c_char, at_flags: c_uint, name: *const c_char);