Sync with upstream vhdl mode v3.35.2.

Sync with upstream vhdl mode v3.35.2.

Ref: http://lists.gnu.org/archive/html/emacs-devel/2014-03/msg01137.html

* lisp/progmodes/vhdl-mode.el (vhdl-version, vhdl-time-stamp): Update.
(top-level): No longer require assoc.
(vhdl-asort, vhdl-anot-head-p, vhdl-aput, vhdl-adelete, vhdl-aget):
New functions.  Use throughout to replace aget etc.
(vhdl-aput-delete-if-nil): Rename from vhdl-aput.
(vhdl-update-file-contents): Update for vhdl-aput-delete-if-nil rename.
(vhdl-template-replace-header-keywords): Fix bug for "<title string>".
(vhdl-compile-init): Do not initialize regexps for Emacs 22+.
(vhdl-error-regexp-emacs-alist): Remove regexps from all compilers
except `vhdl-compiler'.
(vhdl-error-regexp-add-emacs): Remove all other compilers,
when appropriate.