perf script: Don't display trace info when invoking scripts

Only display the trace info if using the default event display.  When
invoking scripts we assume they have complete control of what's
displayed so we shouldn't unconditionally display the trace info, and
when generating scripts we don't expect to see trace info obscuring the
output message.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Link: http://lkml.kernel.org/r/12ec084ef2870178915c907d16cd1dfa19fbb39e.1358527965.git.tom.zanussi@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>