vimrc: refactor CloseIfOnlyNerdTreeLeft.
vimrc: refactor CloseIfOnlyNerdTreeLeft.

Rename it to CloseIfOnlyControlWinLeft and also close if the last window
is a quickfix list.

scorpiovn/dotfiles,blueyed/dotfiles,blueyed/dotfiles,blueyed/dotfiles,blueyed/dotfiles,scorpiovn/dotfiles,scorpiovn/dotfiles,blueyed/dotfiles,scorpiovn/dotfiles,scorpiovn/dotfiles