[flang] Fix rank and byte stride in pointer remapping

[clementval]

Summary

In some remapping case the rank of the pointer is different
from the target one.

program remap
  type :: p
    integer :: a
  end type t
  type(p), target :: ta(10) = [ (t(i),i=1,10) ]
  class(t), pointer :: p(:,:)
  p(1:2,1:5) => ta
end

This patch updates the rank and the byte stride to fix such case.

[klausler]

Looks great; thank you for debugging this.

flang/runtime/pointer.cpp

 void RTNAME(PointerAssociateRemapping)(Descriptor &pointer,
     const Descriptor &target, const Descriptor &bounds, const char *sourceFile,
     int sourceLine) {
   pointer = target;
   pointer.raw().attribute = CFI_attribute_pointer;
   Terminator terminator{sourceFile, sourceLine};
   SubscriptValue byteStride{/*captured from first dimension*/};
   std::size_t boundElementBytes{bounds.ElementBytes()};
+  pointer.raw().rank = bounds.rank();
   for (int j{0}; j < bounds.rank(); ++j) {
     auto &dim{pointer.GetDimension(j)};
     dim.SetBounds(GetInt64(bounds.ZeroBasedIndexedElement<const char>(2 * j),
                       boundElementBytes, terminator),
         GetInt64(bounds.ZeroBasedIndexedElement<const char>(2 * j + 1),
             boundElementBytes, terminator));
     if (j == 0) {
-      byteStride = dim.ByteStride();
+      byteStride = dim.ByteStride() * dim.Extent();
     } else {
       dim.SetByteStride(byteStride);
       byteStride *= dim.Extent();
     }
   }
   if (pointer.Elements() > target.Elements()) {
     terminator.Crash("PointerAssociateRemapping: too many elements in remapped "
                      "pointer (%zd > %zd)",