libbpf: Fix BTF dedup to support recursive typedef definitions

libbpf: Fix BTF dedup to support recursive typedef definitions

Handle recursive typedefs in BTF deduplication

Pahole fails to encode BTF for some Go projects (e.g. Kubernetes and
Podman) due to recursive type definitions that create reference loops
not representable in C. These recursive typedefs trigger a failure in
the BTF deduplication algorithm.

This patch extends btf_dedup_ref_type() to properly handle potential
recursion for BTF_KIND_TYPEDEF, similar to how recursion is already
handled for BTF_KIND_STRUCT. This allows pahole to successfully
generate BTF for Go binaries using recursive types without impacting
existing C-based workflows.

Suggested-by: Tristan d'Audibert <tristan.daudibert@gmail.com>
Co-developed-by: Martin Horth <martin.horth@telecom-sudparis.eu>
Co-developed-by: Ouail Derghal <ouail.derghal@imt-atlantique.fr>
Co-developed-by: Guilhem Jazeron <guilhem.jazeron@inria.fr>
Co-developed-by: Ludovic Paillat <ludovic.paillat@inria.fr>
Co-developed-by: Robin Theveniaut <robin.theveniaut@irit.fr>
Signed-off-by: Martin Horth <martin.horth@telecom-sudparis.eu>
Signed-off-by: Ouail Derghal <ouail.derghal@imt-atlantique.fr>
Signed-off-by: Guilhem Jazeron <guilhem.jazeron@inria.fr>
Signed-off-by: Ludovic Paillat <ludovic.paillat@inria.fr>
Signed-off-by: Robin Theveniaut <robin.theveniaut@irit.fr>
Signed-off-by: Paul Houssel <paul.houssel@orange.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/bf00857b1e06f282aac12f6834de7396a7547ba6.1763037045.git.paul.houssel@orange.com