This provides a new set of bitmasked headers. A new field is
added in the perf headers that implements a bitmap storing
optional features present in the perf.data file.

The layout can be pictured like this:

(Usual perf headers)(Features bitmap)[Feature 0][Feature
n][Feature 255]

If the bit n is set, then the feature n is used in this file.
They are all set in order. This brings a backward and forward
compatibility.

The trace_info section has moved into such optional features,
this is the first and only one for now.

This is backward compatible with the .32 file version although
it doesn't support the previous separate trace.info file.

And finally it doesn't support the current interim development
version.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1255792354-11304-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>