Remove libbabeltrace check from default features set, because the
requested version is not released yet in most distributions. We'll
enable later.

Calling libbabeltrace check manually via feature_check before
$(feature-libbabeltrace) is used.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <david.ahern@oracle.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-5n7mr6ugcwdbxk0n1z8uukaa@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>