ir, test-read-ctf: Remove uncertainty in sorting anonymous types

ir, test-read-ctf: Remove uncertainty in sorting anonymous types

For a reason, I am seeing changes in the test-read-ctf output.  Those
are related to sorting anonymous structs that have no (internal) name.
The CTF reader emits such types.

This patch thus considers the flat representation of an anonymous
class/union when it doesn't have an internal name.  The patch also
updates the test-read-ctf output tests accordingly.

	* src/abg-ir.cc ({class_decl,
	union_decl}::get_pretty_representation): If the anonymous class
	has no internal name, use its flat representation as internal
	representation.
	* tests/data/test-read-ctf/test-PR26568-1.o.abi: Likewise.
	* tests/data/test-read-ctf/test-PR26568-2.o.abi: Likewise.
	* tests/data/test-read-ctf/test-anonymous-fields.o.abi: Likewise.
	* tests/data/test-read-ctf/test-anonymous-fields.o.abi: Likewise.
	* tests/data/test-read-ctf/test0.hash.abi: Likewise.

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