Otherwise 'perf trace' leaves a temporary file /tmp/perf-vdso.so-XXXXXX.

  $ perf trace -o log true
  $ ls -l /tmp/perf-vdso.*
  -rw------- 1 root root 8192 Nov  8 03:08 /tmp/perf-vdso.so-5bCpD0
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vasily Averin <vvs@virtuozzo.com>
Link: http://lkml.kernel.org/r/20171108002246.8924-1-avagin@openvz.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>