Most uses of the evsel constructor are followed by a call to
perf_evlist__add with an idex of evlist->nr_entries, so make rename
the current constructor to perf_evsel__new_idx and remove the need
for passing the constructor for the common case.

We still need the new_idx variant because the way groups are handled,
with evsel->nr_members holding the number of entries in an evlist,
partitioning the evlist into sublists inside a single linked list.

This asks for a clarifying refactoring, but for now simplify the non
parser cases, so that tool writers don't have to bother with evsel idx
setting.

Cc: Adrian Hunter <adrian.hunter@intel.com>
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: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-zy9tskx6jqm2rmw7468zze2a@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>