unix: add missing syscalls on AIX

Access, Chmod, Chown and Creat were forgotten when porting the package
on AIX.

Fixes golang/go#42001

Change-Id: I1ab8c5198240421b31db8b447fe37ce5d80e5ce8
Reviewed-on: https://go-review.googlesource.com/c/sys/+/262897
Trust: Tobias Klauser <[email protected]>
Run-TryBot: Tobias Klauser <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Tobias Klauser <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: Helflym

unix/syscall_aix.go

@@ -19,6 +19,22 @@ import "unsafe"
  * Wrapped
  */
 
+func Access(path string, mode uint32) (err error) {
+	return Faccessat(AT_FDCWD, path, mode, 0)
+}
+
+func Chmod(path string, mode uint32) (err error) {
+	return Fchmodat(AT_FDCWD, path, mode, 0)
+}
+
+func Chown(path string, uid int, gid int) (err error) {
+	return Fchownat(AT_FDCWD, path, uid, gid, 0)
+}
+
+func Creat(path string, mode uint32) (fd int, err error) {
+	return Open(path, O_CREAT|O_WRONLY|O_TRUNC, mode)
+}
+
 //sys	utimes(path string, times *[2]Timeval) (err error)
 func Utimes(path string, tv []Timeval) error {
 	if len(tv) != 2 {