perf report: Create auxiliary trace data files for s390

Create auxiliary trace data log files when invoked with option
--itrace=d as in:

  [root@s35lp76 perf] perf report -i perf.data.aux1 --stdio --itrace=d

perf report creates several data files in the current directory named
aux.smp.## where ## is a 2 digit hex number with leading zeros
representing the CPU number this trace data was recorded from. The file
contents is binary and contains the CPU-Measurement Sampling Data Blocks
(SDBs).

The directory to save the auxiliary trace buffer can be changed using
the perf config file and command. Specify section 'auxtrace' keyword
'dumpdir' and assign it a valid directory name. If the directory does
not exist or has the wrong file type, the current directory is used.

  [root@p23lp27 perf]# perf config auxtrace.dumpdir=/tmp
  [root@p23lp27 perf]# perf config --user -l auxtrace.dumpdir=/tmp
  [root@p23lp27 perf]# perf report ...
  [root@p23lp27 perf]# ll /tmp/aux.smp.00
  -rw-r--r-- 1 root root 204800 Aug  2 13:48 /tmp/aux.smp.00
  [root@p23lp27 perf]#

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180809045650.89197-1-tmricht@linux.ibm.com


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