require 'syscall.ph' seems to have been the point. Today I replaced it by require '/home/users/mg/tmp/sys/syscall.ph' (where I generated syscall.ph yesterday with h2ph) and then the error msg mutated into syntax error at _h2ph_pre.ph line 2, near ".1(". So I commented out two funny lines in /home/users/mg/tmp/_h2ph_pre.ph (itīs not in dir sys):
#unless (defined &A1.1) { sub A1.1() { 1 } }
#unless (defined &S1.1) { sub S1.1() { 1 } }
...and now it works!. I hope this doesnīt blow up some other gory detail.
Thanks for your help.