perf tools: Move init_have_children field to the unnamed union

perf tools: Move init_have_children field to the unnamed union

The init_have_children is used to init callchain info only for TUI.  So
it'd be better to move it to the TUI-specific unnamed union member.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1429687101-4360-3-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>