perf intel-pt: Add support for samples to contain IPC ratio

perf intel-pt: Add support for samples to contain IPC ratio

Copy the incremental instruction count and cycle count onto 'instructions'
and 'branches' samples.

Because Intel PT does not update the cycle count on every branch or
instruction, the incremental values will often be zero.

When there are values, they will be the number of instructions and
number of cycles since the last update, and thus represent the average
IPC since the last IPC value.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190520113728.14389-8-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>