sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   b707659213d3c70f2c704ec950df6263b4bffe84
Checkpoint bpf-next commit: b753c5a7f99f390fc100de18647ce0dcacdceafc
Baseline bpf commit:        f1fc7249dddc0e52d9e805e2e661caa118649509
Checkpoint bpf commit:      91b4db5313a2c793aabc2143efb8ed0cf0fdd097

Andrii Nakryiko (2):
  libbpf: fix missing __WORDSIZE definition
  libbpf: attempt to load kernel BTF from sysfs first

Arnaldo Carvalho de Melo (1):
  tools headers UAPI: Sync if_link.h with the kernel

Daniel Borkmann (1):
  bpf: sync bpf.h to tools infrastructure

 include/uapi/linux/bpf.h     |  4 +--
 include/uapi/linux/if_link.h |  5 +++
 src/hashmap.h                |  5 +++
 src/libbpf.c                 | 64 ++++++++++++++++++++++++++++++++----
 4 files changed, 69 insertions(+), 9 deletions(-)

--
2.17.1

BPF-CHECKPOINT-COMMIT

@@ -1 +1 @@
-f1fc7249dddc0e52d9e805e2e661caa118649509
+91b4db5313a2c793aabc2143efb8ed0cf0fdd097

CHECKPOINT-COMMIT

@@ -1 +1 @@
-b707659213d3c70f2c704ec950df6263b4bffe84
+b753c5a7f99f390fc100de18647ce0dcacdceafc