perf script: Add Instruction Tracing support

perf script: Add Instruction Tracing support

Add support for decoding an AUX area assuming it contains instruction
tracing data.

Signed-off-by: Adrian Hunter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ Do not use -Z as an alternative to --itrace ]
[ Fixed initialization of itrace_synth_opts struct fields on older gcc versions ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>