perf tools: Move TUI-specific fields into unnamed union

Since perf diff only supports stdio output, TUI fields are only accessed
from perf report (or perf top).  So add a new unnamed union and move
struct hist_entry_tui and those TUI-specific fields.

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/1429687101-4360-2-git-send-email-namhyung@kernel.org


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