Set explicit library versioning for Evergreen 2.0 to 2:0:0

Set explicit library versioning for Evergreen 2.0 to 2:0:0

This should help for anything linking to core Evergreen libraries;
as we revise the -version-info number, anything that links against
the core Evergreen libraries will quickly scream if we rev the
interface number without specifying via the age number that previous
interfaces are still supported. Let's remember to revise it
accordingly!

Also remove redundant linkage to oils_idl.

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_0@19142 dcc99617-32d9-48b4-a31d-7c20da2025e4