Display complex data types in gdb-mi

Display complex data types in gdb-mi

* lisp/progmodes/gdb-mi.el (bindat): Require.
(gdb-invalidate-locals): Use `-stack-list-variables` instead of
the deprecated `-stack-list-locals`. Additionally, this allow
function arguments to be displayed in the locals buffer.
(gdb-locals-values-buffer, gdb-locals-values-buffer-name)
(gdb-locals-simple-values-only, gdb-locals-values-table): New
variables.
(gdb-locals-values-handler-custom): Create a new gdb buffer for
extracting local variable values. To
extract the values for 'complex' data-types, the command
`-stack-list-locals` is used with the `--all-values` flag.

The extracted values are then stored in a hash-table for later use in
the `gdb-locals-handler-custom` that performs the actual update of the
Local variable buffer.

All variable values are filtered to fit it into a single line, being
truncated as necessary by the user customizable option
`gdb-locals-value-limit`.

The old behavior of hiding complex values can be restored using the
customizable `gdb-locals-simple-values-only` option.

Patch amended by William Xu <william.xwl@gmail.com>.