Merge branch 'bpf-arena-followups'

Alexei Starovoitov says:

====================
bpf: arena followups.

From: Alexei Starovoitov <ast@kernel.org>

A set of follow ups to clean up bpf_arena and adjust to the latest LLVM.
====================

Link: https://lore.kernel.org/r/20240315021834.62988-1-alexei.starovoitov@gmail.com


Signed-off-by: Andrii Nakryiko <andrii@kernel.org>