[flang] Fix checking of pointer passed to assumed-rank

[klausler]

Summary

Don't check ranks when a pointer actual argument is associated with
a pointer assumed-rank dummy argument.

[PeteSteinfeld]

All builds and tests correctly and looks good.

flang/lib/Semantics/pointer-assignment.cpp

if (!lhsType_) {
               " derived type when target is unlimited polymorphic"_err_en_US;
       }
     } else {
       if (!lhsType_->type().IsTkLenCompatibleWith(rhsType->type())) {
         msg = MessageFormattedText{
             "Target type %s is not compatible with pointer type %s"_err_en_US,
             rhsType->type().AsFortran(), lhsType_->type().AsFortran()};
 
-      } else if (!isBoundsRemapping_) {
+      } else if (!isBoundsRemapping_ &&
+          !lhsType_->attrs().test(TypeAndShape::Attr::AssumedRank)) {
         int lhsRank{evaluate::GetRank(lhsType_->shape())};
         int rhsRank{evaluate::GetRank(rhsType->shape())};
         if (lhsRank != rhsRank) {
           msg = MessageFormattedText{
               "Pointer has rank %d but target has rank %d"_err_en_US, lhsRank,
               rhsRank};
         }
       }