perf tools: Stop using a global trace events description list

The pevent thing is per perf.data file, so I made it stop being static
and become a perf_session member, so tools processing perf.data files
use perf_session and _there_ we read the trace events description into
session->pevent and then change everywhere to stop using that single
global pevent variable and use the per session one.

Note that it _doesn't_ fall backs to trace__event_id, as we're not
interested at all in what is present in the
/sys/kernel/debug/tracing/events in the workstation doing the analysis,
just in what is in the perf.data file.

This patch also introduces perf_session__set_tracepoints_handlers that
is the perf perf.data/session way to associate handlers to tracepoint
events by resolving their IDs using the events descriptions stored in a
perf.data file. Make 'perf sched' use it.

Reported-by: Dmitry Antipov <dmitry.antipov@linaro.org>
Tested-by: Dmitry Antipov <dmitry.antipov@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linaro-dev@lists.linaro.org
Cc: patches@linaro.org
Link: http://lkml.kernel.org/r/20120625232016.GA28525@infradead.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>