sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline commit:   5e2ac390fbd08b2a462db66cef2663e4db0d5191
Checkpoint commit: 2c6a577d719e96c89b1aaa631089cce69b4d0045

Andrii Nakryiko (1):
  libbpf: fix check for presence of associated BTF for map creation

Stanislav Fomichev (1):
  bpf/tools: sync bpf.h

 include/uapi/linux/bpf.h | 2 ++
 src/libbpf.c             | 9 +++++----
 2 files changed, 7 insertions(+), 4 deletions(-)

--
2.17.1

CHECKPOINT-COMMIT

@@ -1 +1 @@
-5e2ac390fbd08b2a462db66cef2663e4db0d5191
+2c6a577d719e96c89b1aaa631089cce69b4d0045