How to regenerate syscall tables ?

[Konstantin Belousov]

I am on today stable/12 with src of today HEAD.  Trying to add a new
syscall, and then regenerating the files, I did 'make buildworld',
then

orion% make sysent                                          ~/build/bsd/DEV/src
make -C /usr/home/kostik/work/build/bsd/DEV/src/sys/kern sysent
flua ../tools/makesyscalls.lua syscalls.master
make[2]: exec(flua) failed (No such file or directory)
*** Error code 1

What is missing ?