concretizer: handle "none" value and '*' wildcard

The "none" variant value cannot be combined with
other values.

The '*' wildcard matches anything, including "none".
It's thus relevant in queries, but disregarded in
concretization.

lib/spack/spack/solver/asp.py

@@ -1150,8 +1150,10 @@ class Body(object):
             value = variant.value
             if isinstance(value, tuple):
                 for v in value:
+                    if v == '*':
+                        continue
                     clauses.append(f.variant(spec.name, vname, v))
-            else:
+            elif value != '*':
                 clauses.append(f.variant(spec.name, vname, variant.value))
 
         # compiler and compiler version
@@ -1424,7 +1426,7 @@ def setup(self, driver, specs):
         possible = spack.package.possible_dependencies(
             *specs,
             virtuals=self.possible_virtuals,
-            deptype=("build", "link", "run")
+            deptype=("build", "link", "run", "test")
         )
         pkgs = set(possible)
 

lib/spack/spack/solver/concretize.lp

@@ -194,6 +194,11 @@ variant_default_value(Package, Variant, Value)
 variant_default_value(Package, Variant, Value)
  :- variant_default_value_from_packages_yaml(Package, Variant, Value).
 
+% Treat 'none' in a special way - it cannot be combined with other
+% values even if the variant is multi-valued
+:- 2 {variant_value(Package, Variant, Value): variant_possible_value(Package, Variant, Value)},
+   variant_value(Package, Variant, "none").
+
 % suppress warnings about this atom being unset.  It's only set if some
 % spec or some package sets it, and without this, clingo will give
 % warnings like 'info: atom does not occur in any rule head'.