perf tools: Reorganize some structs to save space

Using 'pahole --packable' I found some structs that could be reorganized
to eliminate alignment holes, in some cases getting them to be cacheline
multiples.

[acme@doppio linux-2.6-tip]$ codiff perf.old ~/bin/perf
builtin-annotate.c:
  struct perf_session    |   -8
  struct perf_header     |   -8
 2 structs changed

builtin-diff.c:
  struct sample_data         |   -8
 1 struct changed
  diff__process_sample_event |   -8
 1 function changed, 8 bytes removed, diff: -8

builtin-sched.c:
  struct sched_atom      |   -8
 1 struct changed

builtin-timechart.c:
  struct per_pid         |   -8
 1 struct changed
  cmd_timechart          |  -16
 1 function changed, 16 bytes removed, diff: -16

builtin-probe.c:
  struct perf_probe_point |   -8
  struct perf_probe_event |   -8
 2 structs changed
  opt_add_probe_event     |   -3
 1 function changed, 3 bytes removed, diff: -3

util/probe-finder.c:
  struct probe_finder      |   -8
 1 struct changed
  find_kprobe_trace_events |  -16
 1 function changed, 16 bytes removed, diff: -16

/home/acme/bin/perf:
 4 functions changed, 43 bytes removed, diff: -43
[acme@doppio linux-2.6-tip]$

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>