'perf annotate --stdio' will colorize entries with most hits and
possibly some other aspects of its output, but those colors gets
suppressed if we redirect the output to a non-tty, allow keeping the
colors by adding a new option, --stdio-color, now this use case will
also output escape sequences for colors:

  $ perf annotate --stdio-color | more
Based-on-a-patch-by: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-sjrnixani5pg6qez640gaxhf@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>