Optimize c-syntactic-skip-backward, c-determine-limit for large comment blocks

Optimize c-syntactic-skip-backward, c-determine-limit for large comment blocks

* lisp/progmodes/cc-engine.el (c-ssb-lit-begin): Remove.
(c-syntactic-skip-backward): Remove the surrounding c-self-bind-state-cache.
Use the standard function c-literal-start in place of the special purpose
c-ssb-lit-begin.  With a suitable skip-chars argument (the usual case),
optimize by invoking c-backward-syntactic-ws to move back over comment blocks.
(c-determine-limit-get-base): Inovke an early c-backward-syntactic-ws.
(c-determine-limit): Use c-forward-comment whilst moving forward.  Cope with
an empty position stack whilst looking for non-literals (bug fix).  In the
recursive call, double try-size to prevent Lisp stack overflow.