perf dso: Move libunwind dso_data variables into ifdef

perf dso: Move libunwind dso_data variables into ifdef

The variables elf_base_addr, debug_frame_offset, eh_frame_hdr_addr and
eh_frame_hdr_offset are only accessed in unwind-libunwind-local.c
which is conditionally built on having libunwind support. Make the
variables conditional on libunwind support too.

Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: https://lore.kernel.org/r/20250319050741.269828-2-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>