Fix handling of MINIBUF argument in 'walk-window-tree'

* lisp/window.el (walk-window-tree): Handle MINIBUF argument
as advertised when FRAME is minibuffer-only.
(window--resize-apply-p, window--sanitize-window-sizes)
(delete-other-windows, split-window-sensibly): Call
'walk-window-tree' with suitable MINIBUF argument.
1 job for master in 52 minutes and 28 seconds (queued for 2 seconds)
Status Job ID Name Coverage
failed #866


Name Stage Failure
test-all Test
Makefile:309: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
make[2]: *** [check-doit] Error 1
make[1]: *** [check-expensive] Error 2
Makefile:284: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:962: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1