perf trace/scripting: Add rwtop and sctop scripts

A couple of scripts, one in Python and the other in Perl, that
demonstrate 'live mode' tracing.  For each, the output of the
perf event stream is fed continuously to the script, which
continuously aggregates the data and reports the current results
every 3 seconds, or at the optionally specified interval.  After
the current results are displayed, the aggregations are cleared
and the cycle begins anew.

To run the scripts, simply pipe the output of the 'perf trace
record' step as input to the corresponding 'perf trace report'
step, using '-' as the filename to -o and -i:

 $ perf trace record sctop -o - | perf trace report sctop -i -

Also adds clear_term() utility functions to the Util.pm and
Util.py utility modules, for use by any script to clear the
screen.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: fweisbec@gmail.com
Cc: rostedt@goodmis.org
Cc: k-keiichi@bx.jp.nec.com
Cc: acme@ghostprotocols.net
LKML-Reference: <1270184365-8281-10-git-send-email-tzanussi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>