loc_tools.pl: do a 'require' before module's function call

loc_tools.pl: do a 'require' before module's function call

This was failing to do the require before testing if the function in the
module existed, so if the require hadn't been done by someone else, it
would show as not existing, and so would fail unnecessarily.

The other fix is to not assume the require has been done, so in the
right circumstances, this could have an undefined function error.  But
all current uses had already done the require, so this bug has yet to
show up.