burp_ca script does not work if the system does not have a hostname command

[andrekeller]

I modern distros, it's not always guaranteed to have a hostname command. hostnamectl replaces it.
While this is easy to workaround it seems like this restriction is unnecessary.

Looking at https://github.com/grke/burp/blob/master/configs/certs/CA/burp_ca.in it seems that the whole hostname lookup logic runs only to determine the fallback value of the cmdline option. So it could fail silently and the evalution of cmdline arguments could enforce the -n argument if the fallback value is empty.

Not a huge deal though.

[grke]

Thanks for the report, I will try to look at this soon.