sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   c8ee37bde4021a275d2e4f33bd48d54912bb00c4
Checkpoint bpf-next commit: db55174d05ee6bed9d0583ba08e99c891ef0ed05
Baseline bpf commit:        2d311f480b52eeb2e1fd432d64b78d82952c3808
Checkpoint bpf commit:      d900f3d20cc3169ce42ec72acc850e662a4d4db2

Alexei Starovoitov (1):
  bpf: Rename __kptr_ref -> __kptr and __kptr -> __kptr_untrusted.

Daniel Müller (3):
  libbpf: Implement basic zip archive parsing support
  libbpf: Introduce elf_find_func_offset_from_file() function
  libbpf: Add support for attaching uprobes to shared objects in APKs

Joanne Koong (3):
  bpf: Add skb dynptrs
  bpf: Add xdp dynptrs
  bpf: Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr

Tero Kristo (1):
  bpf: Add support for absolute value BPF timers

Viktor Malik (3):
  libbpf: Remove unnecessary ternary operator
  libbpf: Remove several dead assignments
  libbpf: Cleanup linker_append_elf_relos

 include/uapi/linux/bpf.h |  33 +++-
 src/bpf_helpers.h        |   2 +-
 src/btf.c                |   2 -
 src/libbpf.c             | 149 ++++++++++++++----
 src/linker.c             |  11 +-
 src/relo_core.c          |   3 -
 src/zip.c                | 328 +++++++++++++++++++++++++++++++++++++++
 src/zip.h                |  47 ++++++
 8 files changed, 529 insertions(+), 46 deletions(-)
 create mode 100644 src/zip.c
 create mode 100644 src/zip.h

Signed-off-by: Daniel Müller <deso@posteo.net>

BPF-CHECKPOINT-COMMIT

@@ -1 +1 @@
-2d311f480b52eeb2e1fd432d64b78d82952c3808
+d900f3d20cc3169ce42ec72acc850e662a4d4db2

CHECKPOINT-COMMIT

@@ -1 +1 @@
-c8ee37bde4021a275d2e4f33bd48d54912bb00c4
+db55174d05ee6bed9d0583ba08e99c891ef0ed05