Bug 24560 - Assertion failure on an abixml with an anonymous type

Bug 24560 - Assertion failure on an abixml with an anonymous type

When reading an abixml file, we should not try to re-use an anonymous
class, union or enum because by construction two anonymous unions of
the same (internal) name don't necessarily designate the same type.
We already do that in the ELF/DWARF reader so we need to update the
abixml reader too.

Fixed thus.

	* src/abg-reader.cc (read_context::maybe_canonicalize_type): Delay
	canonicalization of union types too.
	(build_class_decl, build_union_decl): Do not try to re-use
	anonymous types.

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