CC Mode: Respect users' settings of open-paren-in-column-0-is-defun-start.

CC Mode: Respect users' settings of open-paren-in-column-0-is-defun-start.

lisp/progmodes/cc-engine.el (c-backward-single-comment, c-backward-comments)
(c-invalidate-state-cache-1, c-parse-state-1, c-guess-basic-syntax):
remove bindings of open-paren-in-column-0-is-defun-start to nil.
(c-get-fallback-scan-pos): "New" function (existed several years ago).
(c-parse-state-get-strategy): Reintroduce the 'BOD strategy, using
c-get-fallback-scan-pos.
(c-parse-state-1): Handle 'BOD strategy.

lisp/progmodes/cc-mode.el (c-before-change, c-after-change)
c-font-lock-fontify-region): remove bindings of
open-paren-in-column-0-is-defun-start to nil.

cc-mode.texi (Performance Issues, Limitations and Known Bugs): Fix mix up
between @chapter and @appendix.