* stack.c: Reformat. Improve comments. Include "valprint.h".

* stack.c: Reformat.  Improve comments.  Include "valprint.h".
(args_info, locals_info, backtrace_command, backtrace_command_1)
(backtrace_full_command, frame_info, frame_command, down_command)
(down_silently_base, down_silently_command, up_command)
(up_silently_base, up_silently_command, parse_frame_specification)
(current_frame_command, print_frame_args_vars, catch_info)
(args_plus_locals_info), print_frame_label_vars)
(print_block_frame_labels, print_block_frame_locals)
(func_command): Remove prototypes.
(print_stack_frame, backtrace_command_stub, backtrace_command,
backtrace_full_command, print_frame_args, print_frame_arg_vars,
print_args_stub, func_command): Remove redundant casts.
(addressprint): Remove extern declaration.
(frame_command): Make static.
(struct print_stack_frame_args, struct print_args_args): Rename
`fi' member to `frame'.
(print_stack_frame, print_frame_nameless_args, print_frame_args)
(set_current_sal_from_frame, print_frame_info, print_frame)
(show_stack_frame, print_block_frame_locals)
(print_frame_local_vars, print_frame_label_vars)
(print_frame_arg_vars, select_and_print_frame): Rename `fi'
argument to `frame'.
(func_command): Rename `fp' variable to `frame'.
(get_language): Restructure.
* Makefile.in (stack.o): Update dependencies.