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.