btf_encoder: Clean up global encoders list

With multithreading moved entirely to the dwarf_loader, now there is
only one btf_encoder. Hence there is no need to maintain a global list
of encoders anymore.

Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mykola Lysenko <mykolal@fb.com>
Link: https://lore.kernel.org/r/20250109185950.653110-10-ihor.solodrai@pm.me
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2 files changed