sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   b3eece09e2e69f528a1ab6104861550dec149083
Checkpoint bpf-next commit: afa12644c877d3f627281bb6493d7ca8f9976e3d
Baseline bpf commit:        4e15507fea70c0c312d79610efa46b6853ccf8e0
Checkpoint bpf commit:      2bdeb3ed547d8822b2566797afa6c2584abdb119

Andrii Nakryiko (4):
  bpf: Switch most helper return values from 32-bit int to 64-bit long
  libbpf: Prevent loading vmlinux BTF twice
  libbpf: Support disabling auto-loading BPF programs
  libbpf: Fix CO-RE relocs against .text section

Colin Ian King (1):
  libbpf: Fix spelling mistake "kallasyms" -> "kallsyms"

Dmitry Yakunin (1):
  bpf: Add SO_KEEPALIVE and related options to bpf_setsockopt

Jesper Dangaard Brouer (1):
  libbpf: Adjust SEC short cut for expected attach type BPF_XDP_DEVMAP

Quentin Monnet (1):
  bpf: Fix formatting in documentation for BPF helpers

Yonghong Song (3):
  bpf: Add bpf_skc_to_tcp6_sock() helper
  bpf: Add bpf_skc_to_{tcp, tcp_timewait, tcp_request}_sock() helpers
  bpf: Add bpf_skc_to_udp6_sock() helper

 include/uapi/linux/bpf.h | 277 ++++++++++++++++++++++-----------------
 src/libbpf.c             |  93 +++++++++----
 src/libbpf.h             |   2 +
 src/libbpf.map           |   2 +
 4 files changed, 233 insertions(+), 141 deletions(-)

--
2.24.1

BPF-CHECKPOINT-COMMIT

@@ -1 +1 @@
-4e15507fea70c0c312d79610efa46b6853ccf8e0
+2bdeb3ed547d8822b2566797afa6c2584abdb119

CHECKPOINT-COMMIT

@@ -1 +1 @@
-b3eece09e2e69f528a1ab6104861550dec149083
+afa12644c877d3f627281bb6493d7ca8f9976e3d