Fix that activation mode default was accidentally changed to single click

Sort of introduced by recent form layout fix for OS X.
Add the missing break statements.

Change-Id: I0862c34f31e4afc7d1834fa436c6193345205b9b
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>

src/plugins/coreplugin/manhattanstyle.cpp

@@ -368,11 +368,13 @@ int ManhattanStyle::styleHint(StyleHint hint, const QStyleOption *option, const
             if (activationMode.isValid())
                 ret = activationMode.toBool();
         }
+        break;
     case QStyle::SH_FormLayoutFieldGrowthPolicy:
         // The default in QMacStyle, FieldsStayAtSizeHint, is just always the wrong thing
         // Use the same as on all other shipped styles
         if (Utils::HostOsInfo::isMacHost())
             ret = QFormLayout::AllNonFixedFieldsGrow;
+        break;
     default:
         break;
     }