Introduce a new dso type DSO_BINARY_TYPE__BPF_PROG_INFO for BPF programs. In
symbol__disassemble(), DSO_BINARY_TYPE__BPF_PROG_INFO dso will call into a new
function symbol__disassemble_bpf() in an upcoming patch, where annotation line
information is filled based bpf_prog_info and btf saved in given perf_env.

Committer notes:

Removed the unnamed union with 'bpf_prog' and 'cache' in 'struct dso',
to fix this bug when exiting 'perf top':

  # perf top
  perf: Segmentation fault
  -------- backtrace --------
  perf[0x5a785a]
  /lib64/libc.so.6(+0x385bf)[0x7fd68443c5bf]
  perf(rb_first+0x2b)[0x4d6eeb]
  perf(dso__delete+0xb7)[0x4dffb7]
  perf[0x4f9e37]
  perf(perf_session__delete+0x64)[0x504df4]
  perf(cmd_top+0x1957)[0x454467]
  perf[0x4aad18]
  perf(main+0x61c)[0x42ec7c]
  /lib64/libc.so.6(__libc_start_main+0xf2)[0x7fd684428412]
  perf(_start+0x2d)[0x42eead]
  #
  # addr2line -fe ~/bin/perf 0x4dffb7
  dso_cache__free
  /home/acme/git/perf/tools/perf/util/dso.c:713

That is trying to access the dso->data.cache, and that is not used with
BPF programs, so we end up accessing what is in bpf_prog.first_member,
b00m.
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/20190312053051.2690567-13-songliubraving@fb.com
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>