perf record: Fix perf.data size in no-buildid mode

perf record: Fix perf.data size in no-buildid mode

The size of perf.data is missing update in no-buildid mode, which gives
wrong output result.

Before this patch:

  $ perf.perf record -B -e syscalls:sys_enter_open uname
  Linux
  [ perf record: Woken up 1 times to  write data ]
  [ perf record: Captured and wrote 0.000 MB perf.data ]

After this patch:

  $ perf.perf record -B -e syscalls:sys_enter_open uname
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data ]

Signed-off-by: He Kuang <hekuang@huawei.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1432819050-30511-1-git-send-email-hekuang@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>