Using struct perf_record_opts to specify how to configure the evsel
perf_event_attrs.

This gets top closer to record in the way it sets up evsels, with the
aim of sharing more and more to the point that both will be a single
utility.

In this direction top now uses the same callchain option parsing as
record and that brings DWARF callchains to top, something that was
already available for record.

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-u03o0bsrqcjgskciso3pvsjr@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>