perf top: Introduce slang based TUI

Disabled by default as there are features found in the stdio based one
that aren't implemented, like live annotation, filtering knobs data
entry.

Annotation hopefully will get somehow merged with the 'perf annotate'
code.

To use it:

perf top --tui

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>