* ada-mode: Use lexical-binding since it requires Emacs-24.2 anyway

* ada-mode: Use lexical-binding since it requires Emacs-24.2 anyway

* ada-mode/ada-mode-compat-23.4.el: Remove.
* ada-mode/ada-build.el: Remove redundant :group arg on defcustoms.
* ada-mode/ada-gnat-compile.el (ada-gnat-fix-error): Remove unused vars
`ident', `type', and `param'.
* ada-mode/ada-gnat-xref.el (ada-gnat-xref-other): Remove unused var `status'.
(ada-gnat-xref-parents): Remove unused vars `found-file', `found-line',
and `found-col'.
(ada-gnat-xref-all): Rename (dynbound) mode-name to (lexbound) mode.
* ada-mode/ada-indent-user-options.el: Remove redundant :group arg
on defcustoms.
* ada-mode/ada-mode.el: Remove redundant :group arg on defcustoms.
(ada-case-exception-file, ada-case-keyword): Comment-out dangerous :safep.
(ada-language-version): Remove redundant calls to make-variable-buffer-local.
(ada-prj-current-file): Declare.
(ada-identifier-at-point): Remove unused var `identifier'.
* ada-mode/gnat-core.el (ada-gnat-ada-name-from-file-name):
Remove unused var `status'.