gui: do not run search while trace still loading
gui: do not run search while trace still loading

Patch fixes a crash if impatient user (like me) makes a search
before trace has been loaded.

Signed-off-by: Tapani Pälli <cdcb67a5e49297de94340ca09f25994bd5e7f762@intel.com>

schulmar/apitrace,surround-io/apitrace,schulmar/apitrace,schulmar/apitrace,trtt/apitrace,EoD/apitrace,surround-io/apitrace,schulmar/apitrace,joshua5201/apitrace,apitrace/apitrace,apitrace/apitrace,joshua5201/apitrace,trtt/apitrace,joshua5201/apitrace,EoD/apitrace,surround-io/apitrace,surround-io/apitrace,schulmar/apitrace,tuanthng/apitrace,swq0553/apitrace,swq0553/apitrace,trtt/apitrace,tuanthng/apitrace,EoD/apitrace,joshua5201/apitrace,swq0553/apitrace,tuanthng/apitrace,trtt/apitrace,apitrace/apitrace,swq0553/apitrace,surround-io/apitrace,trtt/apitrace,apitrace/apitrace,tuanthng/apitrace,EoD/apitrace,joshua5201/apitrace,tuanthng/apitrace,EoD/apitrace,swq0553/apitrace