Fix AbstractionPattern::isNoncopyable to handle archetypes.

This fixes TypeLowering for ~Copyable generics, such as:

struct S<T: ~Copyable>: ~Copyable {
  var x: T
}

extension S: Copyable where T: Copyable  {}

func foo<T>(s: S<T>) -> ()

Previously, TypeLowering would ignore the implicit Copyable
requirement on the archetype 'T'.

lib/SIL/IR/AbstractionPattern.cpp

@@ -290,7 +290,7 @@ bool AbstractionPattern::isNoncopyable(CanType substTy) const {
     
   auto isDefinitelyCopyable = [&](CanType t) -> bool {
     auto result = copyable->getParentModule()
-      ->checkConformanceWithoutContext(substTy, copyable,
+      ->checkConformanceWithoutContext(t, copyable,
                                        /*allowMissing=*/false);
     return result.has_value() && !result.value().isInvalid();
   };