perf: Add 'perf sched' tool

This turn-key tool allows scheduler measurements to be
conducted and the results be displayed numerically.

First baby step towards that goal: clone the new command off of
perf trace.

Fix a few other details along the way:

 - add (minimal) perf trace documentation

 - reorder a few places

 - list perf trace in the mainporcelain list as well
   as it's a very useful utility.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/Documentation/perf-sched.txt

@@ -0,0 +1,25 @@
+perf-sched(1)
+==============
+
+NAME
+----
+perf-sched - Read perf.data (created by perf record) and display sched output
+
+SYNOPSIS
+--------
+[verse]
+'perf sched' [-i <file> | --input=file] symbol_name
+
+DESCRIPTION
+-----------
+This command reads the input file and displays the latencies recorded.
+
+OPTIONS
+-------
+-D::
+--dump-raw-trace=::
+        Display verbose dump of the sched data.
+
+SEE ALSO
+--------
+linkperf:perf-record[1]

tools/perf/Documentation/perf-trace.txt

@@ -0,0 +1,25 @@
+perf-trace(1)
+==============
+
+NAME
+----
+perf-trace - Read perf.data (created by perf record) and display trace output
+
+SYNOPSIS
+--------
+[verse]
+'perf trace' [-i <file> | --input=file] symbol_name
+
+DESCRIPTION
+-----------
+This command reads the input file and displays the trace recorded.
+
+OPTIONS
+-------
+-D::
+--dump-raw-trace=::
+        Display verbose dump of the trace data.
+
+SEE ALSO
+--------
+linkperf:perf-record[1]