According to RFC 2132, 2. BOOTP Extension/DHCP Option Field Format

According to RFC 2132, 2. BOOTP Extension/DHCP Option Field Format
ASCII data should not include trailing NUL but we MUST delete trailing
NULs on receiving.

Jan Vlach ( janus AT volny.cz) reported that Microsoft DHCP server
sends the domain name option with a trailing NUL which the installer
put into /etc/myname as a trailing ^@ which smtpd does not like.

Fix some whitespace while here.

Input & OK millert