Merge branch 'libbpf-extend-linker-api-to-support-in-memory-elf-files'

Alastair Robertson says:

====================
libbpf: Extend linker API to support in-memory ELF files

This gives API consumers the option of using anonymous files/memfds to
avoid writing temporary ELFs to disk, which will be useful for performing
linking as part of bpftrace's JIT compilation.

v3:
- Removed "filename" option. Now always generate our own filename for
  passed-in FDs and buffers.
- Use a common function (bpf_linker_add_file) for shared
  implementation of bpf_linker__add_file, bpf_linker__add_fd and
  bpf_linker__add_buf.
====================

Link: https://patch.msgid.link/20241211164030.573042-1-ajor@meta.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>