Fixed header of "locals and watchers" view

You couldn't disable the 'always adjust column widths to contents' logic
cause of an uninitialized boolean that refused to toggle to false.

src/plugins/debugger/watchwindow.cpp

@@ -55,7 +55,8 @@ enum { INameRole = Qt::UserRole, VisualRole, ExpandedRole };
 /////////////////////////////////////////////////////////////////////
 
 WatchWindow::WatchWindow(Type type, QWidget *parent)
-  : QTreeView(parent), m_type(type)
+    : QTreeView(parent), m_type(type)
+    , m_alwaysResizeColumnsToContents(true)
 {
     setWindowTitle(tr("Locals and Watchers"));
     setAlternatingRowColors(true);