I've enhanced build.sh to support using mk.conf in the same directory
(i.e., the top level of the source tree) if present, instead of /etc/mk.conf.
This is not done if $MAKECONF is already set in the environment.
I.e, the mk.conf / MAKECONF lookup order is now, in descending precedence:
1. MAKECONF in the environment
2. mk.conf at the top of the source tree, if present
3. /etc/mk.conf default from share/mk/bsd.own.mk
This means unprivileged users can benefit from mk.conf(5)
semantics without write privileges to /etc/mk.conf, and
also simplifies per-source-directory configuration.
In all cases, MAKECONF is also set in the generated makewrapper
(it previously wasn't), for consistency with other variables.
Luke.
