perf feature detection: Add -lopcodes to feature-libbfd

Both libbfd and libopcodes are distributed with binutil-dev/devel. When
libbfd is present, it is OK to assume that libopcodes also present. This
has been a safe assumption for bpftool.

This patch adds -lopcodes to perf/Makefile.config. libopcodes will be
used in the next commit for BPF annotation.

Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/20190312053051.2690567-12-songliubraving@fb.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>