perf top: Use the TUI interface by default

To disable it either:

1. Make sure newt-devel is not installed when building it

2. Use 'perf top --stdio' just like with report

3. Edit your ~/.perfconfig or system wide config and have this there:

[tui]

	top = off

But you shouldn't, since the TUI is so much more powerful, has
integration with annotation and where lots more interesting features
will be developed, so if something annoys you (the colors?) just let me
know and I'll do my best to make it pleasant as a default.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-cy2tn4uj1t7c3aqss5l25of5@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>