Sync with upstream vhdl mode v3.38.1.

Sync with upstream vhdl mode v3.38.1.

* lisp/progmodes/vhdl-mode.el (vhdl-version, vhdl-time-stamp): Update.
(vhdl-mode): No longer set comment-padding.
(vhdl-begin-p): Handle missing space between keyword and parenthesis.
(vhdl-beginning-of-statement-1): Fix indentation for "else generate".
(vhdl-template-else, vhdl-template-elsif): Support generate statement.
(vhdl-re-search-forward, vhdl-re-search-backward): Save match data.