meson: use jinja2 for the gperf template

meson: use jinja2 for the gperf template

Jinja2 inserts an empty line after the first macro body, which I don't know how
to get rid of. Only the first macro causes problems: the other ones don't have
conditional statements at the end and the issue does not occur. As a work-around
I moved ProtectHostname to the end of the first macro.

Output is identical, except for horizontal whitespace and change in position of
ProtectHostname.