concretizer: swap priority of selecting provider and default variant (#20182)

refers #20040

Before this PR optimization rules would have selected default
providers at a higher priority than default variants. Here we
swap this priority and we consider variants that are forced by
any means (root spec or spec in depends_on clause) the same as
if they were with a default value.

This prevents the solver from avoiding expected configurations
just because they contain directives like:

depends_on('pkg+foo')

and `+foo` is not the default variant value for pkg.

0 files changed, 0 insertions, 0 deletions