Clean up gdb-mi's usage of display-buffer.

Clean up gdb-mi's usage of display-buffer.

* progmodes/gdb-mi.el (gdb-display-buffer-other-frame-action): New
variable, replacing gdb-frame-parameters.
(gdb-frame-io-buffer, gdb-frame-breakpoints-buffer)
(gdb-frame-threads-buffer, gdb-frame-memory-buffer)
(gdb-frame-disassembly-buffer, gdb-frame-stack-buffer)
(gdb-frame-locals-buffer, gdb-frame-registers-buffer): Use it.
(def-gdb-frame-for-buffer): Macro deleted.  It is easier to define
the functions directly with gdb-display-buffer-other-frame-action.
(gdb-display-breakpoints-buffer, gdb-display-threads-buffer)
(gdb-display-memory-buffer, gdb-display-disassembly-buffer)
(gdb-display-stack-buffer, gdb-display-locals-buffer)
(gdb-display-registers-buffer): Define directly.
(def-gdb-display-buffer): Macro deleted.
(gdb-display-buffer): Remove second and third args, callers don't
use them.  Defer to the default display-buffer behavior, apart
from making windows dedicated.
(gdb-setup-windows): Don't call display-buffer unnecessarily.

* window.el (display-buffer-pop-up-frame): Handle a
pop-up-frame-parameters alist entry.
(display-buffer): Document it.

* progmodes/gud.el (gud-display-line): Just use display-buffer.