I don't think Perl is doing it. I found this stackoverflow discussion where someone ran the unix program ps to show the running processes and it showed the value passed in argv[0] as the process name. So it looks like the os uses that first argument to allow you to have a nicer name than the full path it was invoked as.

Thanks for posting the question, it was interesting to learn about and it got me to compile a c program for the first time in a long while, and on a Raspberry Pi at that.