Save libdir and datadir in why3.conf (fix #595)
With this change, make bench-api
now succeeds on an installation with relocation enabled (after calling why3 config detect
once).
Config.libdir
and Config.datadir
are no longer used in the Why3 library, except when creating a default configuration which is immediately overridden if the user config file exists. They are still used by why3
commands.