In bisect-runner.pl, add -L/usr/local/lib in a non-OS-specific way.

In bisect-runner.pl, add -L/usr/local/lib in a non-OS-specific way.

It's not scalable to hack the hints file on an OS by OS basis to add
-L/usr/local/lib to ldflags, given that in reality any OS will need it, if
it happens to have "wanted" libraries installed in /usr/local. So apply
the relevant logic that deals with this in perl-5.001n's Configure to earlier
versions of Configure.

With this, we can remove the special case to add -L/usr/local/lib for
FreeBSD, and avoid writing similar code for OpenBSD.