Log Message:
Correct sed(1) usage for NetBSD-6.x in the install stage

NetBSD-7.99.25
$ /usr/bin/sed -n '/.*<em:id>\(.*\)<\/em:id>.*/{s//\1/p;q}' install.rdf
{847b3a00-7ab1-11d4-8f02-006008948af5}
$ /usr/bin/sed -n '/.*<em:id>\(.*\)<\/em:id>.*/{s//\1/p;q;}' install.rdf
{847b3a00-7ab1-11d4-8f02-006008948af5}

NetBSD-6.1_STABLE
$ /usr/bin/sed -n '/.*<em:id>\(.*\)<\/em:id>.*/{s//\1/p;q}' install.rdf
sed: 1: "/.*<em:id>\(.*\)<\/em:i ...": extra characters at \ 
the end of q command
$ /usr/bin/sed -n '/.*<em:id>\(.*\)<\/em:id>.*/{s//\1/p;q;}' install.rdf
{847b3a00-7ab1-11d4-8f02-006008948af5}

Closes PR pkg/50264 by Hauke Fath
Solution suggested by David Holland