Fix some indentation problem with \; and pipes.

Fix some indentation problem with \; and pipes.
* lisp/progmodes/sh-script.el (sh-mode-syntax-table): Set syntax of ;|&.
(sh-smie--default-forward-token, sh-smie--default-backward-token):
New functions.
(sh-smie-sh-forward-token, sh-smie-sh-backward-token)
(sh-smie-rc-forward-token, sh-smie-rc-backward-token): Use them.
(sh-smie-sh-rules): Fix indentation of a pipe at BOL.

Fixes: debbugs:17842