perf intel-pt: Factor out common code synthesizing event samples

Factor out common code in functions synthesizing event samples i.e.
intel_pt_synth_branch_sample(), intel_pt_synth_instruction_sample() and
intel_pt_synth_transaction_sample().

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1495786658-18063-27-git-send-email-adrian.hunter@intel.com


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