Fix GDB/MI inline completion.

Fix GDB/MI inline completion.

* progmodes/gdb-mi.el (gdb-input): Accept command and handler
function as separate arguments.
(gdb-init-1, gdb-non-stop-handler, gdb-check-target-async)
(gdb-tooltip-print-1, gud-watch, gdb-speedbar-update)
(gdb-var-list-children, gdb-var-set-format, gdb-var-delete-1)
(gdb-var-delete-children, gdb-edit-value, gdb-var-update)
(gdb-stopped, def-gdb-auto-update-trigger)
(gdb-place-breakpoints, gdb-select-thread, gdb-select-frame)
(gdb-get-changed-registers, gdb-get-main-selected-frame): Callers
changed.
(gud-gdbmi-completions): New function.
(gdb): Use it for generating the completion table.

* progmodes/gud.el (gud-gdb-fetch-lines-filter): Just use
gud-gdb-marker-filter without taking it as an argument.
(gud-gdb-run-command-fetch-lines): Caller changed.
(gud-gdb-completion-function): New variable.
(gud-gdb-completion-at-point): Use it.
(gud-gdb-completions-1): Split from gud-gdb-completions.