Currently, the three Guile versions and their dependent ports conflict, preventing installation of more than one at a time. This is clearly unsatisfactory, so here is a fix for it.
What this does:
- Creates USES=guile[:options] and updates ports to use it.
- To help with conflicts over .pc files, USES=pkgconfig now allows you to specify PKGCONFIG_PATHS to allow management of PKG_CONFIG_PATHS in a cooperative fashion.
- Some specific Guile library ports (guile-lib, guile-cairo, slib-guile) have been flavorized.
- Currently none of the lang/guileN ports install a plain "guile", they install guile1, guile-1.8, guile2, guile-2.2, guile3, guile-3.0 respectively. This could be changed; should "guile" refer to the latest version, or the default version?
- some PORTREVISIONs in this patch will be wrong, this will be re-checked after testing is complete