perf record: Let user have timestamps with per-thread recording

If the option -T is used with option --per-thread, then time is still
not sampled.  Fix that by using OPT_BOOLEAN_SET to distinguish when the
user used the -T option as opposed to the default case when timestamps
are enabled but only for per-cpu recording.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1436183461-1918-1-git-send-email-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>