perf auxtrace: Fix itrace defaults for perf script

perf auxtrace: Fix itrace defaults for perf script

Commit 4eb068157121 ("perf script: Make itrace script default to all
calls") does not work for the case when '--itrace' only is used, because
default_no_sample is not being passed.

Example:

 Before:

  $ perf record -e intel_pt/cyc/u ls
  $ perf script --itrace > cmp1.txt
  $ perf script --itrace=cepwx > cmp2.txt
  $ diff -sq cmp1.txt cmp2.txt
  Files cmp1.txt and cmp2.txt differ

 After:

  $ perf script --itrace > cmp1.txt
  $ perf script --itrace=cepwx > cmp2.txt
  $ diff -sq cmp1.txt cmp2.txt
  Files cmp1.txt and cmp2.txt are identical

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 4eb068157121 ("perf script: Make itrace script default to all calls")
Link: http://lkml.kernel.org/r/20190520113728.14389-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>