Relax check in moduleMatchingVariant

Pull request #317 made the equality check in moduleMatchingVariant
more correct by comparing the variant maps instead of the names.
Using only the names effectively ignores any variation with an
empty name.  Unfortuantely this broke a current user of
ReplaceDependenciesIf.  Go back to the relaxed check for now.

Test: build on a branch with sdk modules
Change-Id: I11016c8df7bd91fd022d04fd3033756f54d7fa0b

context.go

@@ -2733,7 +2733,7 @@ func (c *Context) moduleMatchingVariant(module *moduleInfo, name string) *module
 	}
 
 	for _, m := range group.modules {
-		if module.variant.variations.equal(m.moduleOrAliasVariant().variations) {
+		if module.variant.name == m.moduleOrAliasVariant().name {
 			return m.moduleOrAliasTarget()
 		}
 	}