(gdb-find-file-unhook): Delete variable.
(gdb-set-gud-minor-mode, gdb-set-gud-minor-mode): Delete functions.
(gdb-set-gud-minor-mode-existing-buffers, gdb-init-2): Use GDB
command "info sources". Move calls to GDB command "list".
(gdb-find-file-hook): Just use gdb-source-file-list.
(gdb-source-file-regexp): Use regexp for pre-GDB 6.4.
(gdb-source-file-regexp-1): New regexp for GDB 6.4+ only.
(gdb-set-gud-minor-mode-existing-buffers-1): Use it.
(gdb-data-list-register-values-handler): Use correct trigger name.