[ToolButton] Call update() from setMultiIcon

Fixes issue with reload/stop button not being correctly updated
with themes that use multiIcon for this button.

src/lib/tools/toolbutton.cpp

@@ -55,6 +55,8 @@ void ToolButton::setMultiIcon(const QPixmap &icon)
 
     m_options |= MultiIconOption;
     setFixedSize(m_normalIcon.size());
+
+    update();
 }
 
 QString ToolButton::themeIcon() const