menuconfig: Always show implicit submenus with visible nodes
menuconfig: Always show implicit submenus with visible nodes

Currently, the symbol BAR below (which ends up indented in an implicit
submenu) is shown only if DEP is non-n (or if show-all mode is
enabled):

  config FOO
  	bool "foo" if DEP
  	default y

  config BAR
  	bool "bar" if FOO

This is bad, because it hides visible symbols from the interface. The
assumption was that an implicit submenu (which is only created if the
parent has a prompt) would never have visible items when the root item
is invisible, but prompt-specific conditions and select/imply can break
that assumption.

Fix it by always showing implicit submenus with visible nodes, along
with the parent node. If the parent node is invisible, show it in red,
like in show-all mode (which happens automatically). That's probably
better than having mysteriously indented nodes when the parent is
invisible.

ulfalizer/Kconfiglib,ulfalizer/Kconfiglib