(gud-watch, gdb-invalidate-registers-1)

(gud-watch, gdb-invalidate-registers-1)
(gdb-get-changed-registers): Test value of gud-minor-mode relative
to gud-comint-buffer.
(gdb-speedbar-expand-node, gdb-locals-mode): Use functions in
gdb-ui.el for gdb-mi.el.
(gdb-post-prompt, gdb-get-changed-registers): Move test for
registers buffer to gdb-get-changed-registers.
(gdb-breakpoint-regexp): New regexp.  Allow toggling and
deletion of catchpoints (throw and catch).
(gdb-toggle-breakpoint, gdb-delete-breakpoint)
(gdb-goto-breakpoint): Use it for both gdb-ui and gdb-mi.
(gdb-find-file-hook, gdb-set-gud-minor-mode-existing-buffers-1)
(gdb-var-list-children-1, gdb-info-breakpoints-custom)
(gdb-var-update-1, gdb-invalidate-locals-1): Use also for gdb-mi.