sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   a6ed02cac690b635dbb938690e795812ce1e14ca
Checkpoint bpf-next commit: 35b9211c0a2427e8f39e534f442f43804fc8d5ca
Baseline bpf commit:        1712b2fff8c682d145c7889d2290696647d82dab
Checkpoint bpf commit:      08dc225d8868d5094ada62f471ebdfcce9dbc298

Alexei Starovoitov (1):
  libbpf: Add support for program extensions

Andrii Nakryiko (2):
  libbpf: Improve handling of failed CO-RE relocations
  libbpf: Fix realloc usage in bpf_core_find_cands

Antoine Tenart (1):
  net: macsec: introduce the macsec_context structure

Martin KaFai Lau (1):
  bpf: Sync uapi bpf.h to tools/

 include/uapi/linux/bpf.h     |  10 +++-
 include/uapi/linux/if_link.h |   7 +++
 src/bpf.c                    |   3 +-
 src/libbpf.c                 | 112 +++++++++++++++++++++--------------
 src/libbpf.h                 |   8 ++-
 src/libbpf.map               |   2 +
 src/libbpf_probes.c          |   1 +
 7 files changed, 97 insertions(+), 46 deletions(-)

--
2.17.1
diff --git a/BPF-CHECKPOINT-COMMIT b/BPF-CHECKPOINT-COMMIT
index 8148b1d..8b3e33d 100644
--- a/BPF-CHECKPOINT-COMMIT
+++ b/BPF-CHECKPOINT-COMMIT
@@ -1 +1 @@
-1712b2fff8c682d145c7889d2290696647d82dab
+08dc225d8868d5094ada62f471ebdfcce9dbc298
diff --git a/CHECKPOINT-COMMIT b/CHECKPOINT-COMMIT
index 04dfe1f..0b9b4d7 100644
--- a/CHECKPOINT-COMMIT
+++ b/CHECKPOINT-COMMIT
@@ -1 +1 @@
-a6ed02cac690b635dbb938690e795812ce1e14ca
+35b9211c0a2427e8f39e534f442f43804fc8d5ca