Log Message:
Remove mk/autoconf.mk and mk/automake.mk and replace their usage with
USE_TOOLS and any of "autoconf", "autoconf213", \ 
"automake" or
"automake14".  Also, we don't need to call the auto* tools via
${ACLOCAL}, ${AUTOCONF}, etc., since the tools framework takes care
to symlink the correct tool to the correct name, so we can just use
aclocal, autoconf, etc.