Use QFileInfo::exist(f) instead of QFileInfo(f).exists() if possible

Faster.

Change-Id: I91aa67462e11ff3258600d7f158de79942d0dc81
Reviewed-by: Marc Reilly <marc.reilly@gmail.com>
Reviewed-by: Christian Stenger <christian.stenger@digia.com>

src/plugins/projectexplorer/abstractprocessstep.cpp

@@ -203,10 +203,8 @@ void AbstractProcessStep::run(QFutureInterface<bool> &fi)
         }
     }
 
-
-
     QString effectiveCommand = m_param.effectiveCommand();
-    if (!QFileInfo(effectiveCommand).exists()) {
+    if (!QFileInfo::exists(effectiveCommand)) {
         processStartupFailed();
         fi.reportResult(false);
         emit finished();