bpf: Sync bpf headers in tooling infrastucture

Synchronize tools/include/uapi/linux/bpf.h which was missing changes
from various commits:

  - f3c45326 ("bpf: Document PROG_TEST_RUN limitations")
  - e5e35e75 ("bpf: BPF-helper for MTU checking add length input")

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>