Late canonicalize all types that reference classes when reading DWARF

Late canonicalize all types that reference classes when reading DWARF

Until now, the DWARF reader would late canonicalize typedefs to
classes, as well as classes.  That is not enough.  Let's also
late-canonicalize pointers, references and array of classes too.  This
is because classes that might not be finished yet might be referenced
by those types, and so we want to wait until they are finished before
we canonicalize them.

	* include/abg-fwd.h (peel_array_type): Declare new function.
	* src/abg-ir.cc (peel_array_type): Define it.
	(peel_typedef_pointer_or_reference_type): Peel arrays too, to get
	the type of its element.
	* src/abg-dwarf-reader.cc (maybe_canonicalize_type): If a pointer,
	reference, array or typedef references a class, then do
	late-canonicalize this type.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>