Switch to side-by-side view

--- a/src/qtgui/recoll.h
+++ b/src/qtgui/recoll.h
@@ -22,7 +22,6 @@
 #include "rclconfig.h"
 #include "rcldb.h"
 #include "rclutil.h"
-#include "ptmutex.h"
 
 #include <QString>