perf check: Add libbabeltrace to the listed features

perf check: Add libbabeltrace to the listed features

This enables scripts to more easily determine if `perf data --to-ctf`
is supported.

Committer testing:

  $ perf check feature libbabeltrace
         libbabeltrace: [ on  ]  # HAVE_LIBBABELTRACE_SUPPORT
  $ perf check feature -q libbabeltrace && echo have libbabeltrace support
  have libbabeltrace support
  $

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Derek Foreman <derek.foreman@collabora.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>