perf script/python: Print array argument as string

With the Sebastian's change of handling num array argument (of raw
syscall enter), the script still failed to work like this:

  $ perf record -e raw_syscalls:* sleep 1
  $ perf script -g python
  $ perf script -s perf-script.py
  ...
  Traceback (most recent call last):
    File "perf-script.py", line 42, in raw_syscalls__sys_enter
      (id, args),
  TypeError: %u format: a number is required, not list
  Fatal Python error: problem in Python trace event handler
  Aborted (core dumped)

This is because the generated script tries to print the array arg as
unsigned integer (%u).  Since the python seems to convert arguments to
strings by default, just using %s solved the problem for me.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: http://lkml.kernel.org/r/1401338695-18837-1-git-send-email-namhyung@kernel.orgSigned-off-by: Jiri Olsa <jolsa@kernel.org>

tools/perf/util/scripting-engines/trace-event-python.c

@@ -623,6 +623,7 @@ static int python_generate_script(struct pevent *pevent, const char *outfile)
 			fprintf(ofp, "%s=", f->name);
 			if (f->flags & FIELD_IS_STRING ||
 			    f->flags & FIELD_IS_FLAG ||
+			    f->flags & FIELD_IS_ARRAY ||
 			    f->flags & FIELD_IS_SYMBOLIC)
 				fprintf(ofp, "%%s");
 			else if (f->flags & FIELD_IS_SIGNED)