perf report: Introduce special handling for pipe input

Adds special treatment for stdin - if the user specifies '-i -'
to perf report, the intent is that the event stream be written
to stdin rather than from a disk file.

The actual handling of the '-' filename is done by the session;
this just adds a signal handler to stop reporting, and turns off
interference by the pager.

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: <1270184365-8281-4-git-send-email-tzanussi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>