runtime_loader: Fix missing include of util/kernel_cpp.h.

Due to the missing include, the builtin new and delete operators were
used in those two files instead of the ones from the include used
everywhere else in the runtime_loader.
BMenu: don't invalidate layout when changing marked item

* The layout does not need to change. The label may change in
SetLabelFromMarked mode, but this only affects the layout of the parent
menu.
* This would crash when programatically changing the menu marked item
while the menu is open.