lib/oelite: handle PREFERRED_VERSION's without PREFERRED_PROVIDER's
lib/oelite: handle PREFERRED_VERSION's without PREFERRED_PROVIDER's

When choosing among multiple providers, check PREFERRED_VERSION_*,
and when found, drop all other versions of that recipe.

hundeboll/core,sknsean/core,hundeboll/core,sknsean/core,sknsean/core,sknsean/core,diorcety/oe-lite-core,hundeboll/core,hundeboll/core,diorcety/oe-lite-core,sknsean/core