sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   dc37dc617fabfb1c3a16d49f5d8cc20e9e3608ca
Checkpoint bpf-next commit: 8cbf062a250ed52148badf6f3ffd03657dd4a3f0
Baseline bpf commit:        fe68195daf34d5dddacd3f93dd3eafc4beca3a0e
Checkpoint bpf commit:      61d06f01f9710b327a53492e5add9f972eb909b3

Alexei Starovoitov (1):
  libbpf: Prepare light skeleton for the kernel.

Jakub Sitnicki (1):
  selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup

Marco Elver (1):
  perf: uapi: Document perf_event_attr::sig_data truncation on 32 bit
    architectures

Toke Høiland-Jørgensen (1):
  libbpf: Use dynamically allocated buffer when receiving netlink
    messages

 include/uapi/linux/bpf.h        |   3 +-
 include/uapi/linux/perf_event.h |   2 +
 src/gen_loader.c                |  15 ++-
 src/netlink.c                   |  55 +++++++++-
 src/skel_internal.h             | 185 ++++++++++++++++++++++++++++----
 5 files changed, 234 insertions(+), 26 deletions(-)

--
2.30.2

BPF-CHECKPOINT-COMMIT

@@ -1 +1 @@
-fe68195daf34d5dddacd3f93dd3eafc4beca3a0e
+61d06f01f9710b327a53492e5add9f972eb909b3

CHECKPOINT-COMMIT

@@ -1 +1 @@
-dc37dc617fabfb1c3a16d49f5d8cc20e9e3608ca
+8cbf062a250ed52148badf6f3ffd03657dd4a3f0