perf evsel: Decode read_format and sample_type in perf_evsel__fprintf

Before those fields showed just a number, now it decodes each bit:

[root@sandy linux]# perf evlist -v
cycles: sample_freq=4000, size: 96, sample_type: IP|TID|TIME|CPU|PERIOD, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING|ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, sample_id_all: 1, exclude_guest: 1

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-64ezdtiijolgti08ae3phxyj@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>