sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   35b9211c0a2427e8f39e534f442f43804fc8d5ca
Checkpoint bpf-next commit: 5327644614a18f5d0ff845844a4e9976210b3d8d
Baseline bpf commit:        08dc225d8868d5094ada62f471ebdfcce9dbc298
Checkpoint bpf commit:      41f57cfde186dba6e357f9db25eafbed017e4487

Andrii Nakryiko (1):
  libbpf: Relax check whether BTF is mandatory

Daniel Xu (1):
  selftests/bpf: Add bpf_read_branch_records() selftest

Toke Høiland-Jørgensen (2):
  bpf, uapi: Remove text about bpf_redirect_map() giving higher
    performance
  libbpf: Sanitise internal map names so they are not rejected by the
    kernel

 include/uapi/linux/bpf.h | 41 ++++++++++++++++++++++++++++++----------
 src/libbpf.c             | 12 ++++++++----
 2 files changed, 39 insertions(+), 14 deletions(-)

--
2.17.1

BPF-CHECKPOINT-COMMIT

@@ -1 +1 @@
-08dc225d8868d5094ada62f471ebdfcce9dbc298
+41f57cfde186dba6e357f9db25eafbed017e4487

CHECKPOINT-COMMIT

@@ -1 +1 @@
-35b9211c0a2427e8f39e534f442f43804fc8d5ca
+5327644614a18f5d0ff845844a4e9976210b3d8d