perf tools: Add pmu mappings to header information

With dynamic pmu allocation there are also dynamically assigned pmu ids.
These ids are used in event->attr.type to describe the pmu to be used
for that event. The information is available in sysfs, e.g:

 /sys/bus/event_source/devices/breakpoint/type: 5
 /sys/bus/event_source/devices/cpu/type: 4
 /sys/bus/event_source/devices/ibs_fetch/type: 6
 /sys/bus/event_source/devices/ibs_op/type: 7
 /sys/bus/event_source/devices/software/type: 1
 /sys/bus/event_source/devices/tracepoint/type: 2

These mappings are needed to know which samples belong to which pmu.  If
a pmu is added dynamically like for ibs_fetch or ibs_op the type value
may vary.

Now, when decoding samples from perf.data this information in sysfs
might be no longer available or may have changed. We need to store it in
perf.data. Using the header for this. Now the header information created
with perf report contains an additional section looking like this:

 # pmu mappings: ibs_op = 7, ibs_fetch = 6, cpu = 4, breakpoint = 5, tracepoint = 2, software = 1

Signed-off-by: Robert Richter <robert.richter@amd.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1345144224-27280-9-git-send-email-robert.richter@amd.com


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