perf jit: Add jitdump format specification document

perf jit: Add jitdump format specification document

This patch adds a formal specification of the jitdump format. The goal
is to help jit runtime developers implement the jitdump support without
having to read the jvmti code.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1476356383-30100-10-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>