If you want to set default values for configure scripts to
share, you can create a site shell script called config.site that
gives default values for variables like CC, cache_file,
and prefix. configure looks for
prefix/share/config.site if it exists, then
prefix/etc/config.site if it exists. Or, you can set the
CONFIG_SITE environment variable to the location of the site
script. A warning: not all configure scripts look for a site
script.