This patch comes in two versions: submit.diff with Change.Logs or
submit2.diff with Change2.Logs.

The first fixes the problem by changing array temporaries from class
expressions into class temporaries. This permits the use of
gfc_get_class_from_expr to obtain the vptr for these temporaries and all
the good things that come with that when handling dynamic types. The second
part of the fix is to use the array element length from the class
descriptor, when reallocating on assignment. This is needed because the
vptr is being set too early. I will set about trying to track down why this
is happening and fix it after release.

The second version does the same as the first but puts in place a load of
tidying up that is permitted by the fix to class array temporaries.

I couldn't readily see how to prepare a testcase - ideas?

Both regtest on FC33/x86_64. The first was tested by Dominique (see the
PR). OK for master?

Regards

Paul