CC Mode: Minor corrections and tidy ups for cache invalidation

CC Mode: Minor corrections and tidy ups for cache invalidation

These cache variables are c-lit-pos-cache-limit,
c-semi-near-cache-limit, c-full-near-cache-limit, and
c-state-cache-invalid-pos.

* lisp/progmodes/cc-awk.el
(c-awk-set-string-regexp-syntax-table-properties): Invalidate
the caches after changing the 'syntax-table property.

* lisp/progmodes/cc-defs.el (c-put-string-fence-trim-caches):
New macro.
(c-unmark-<-or->-as-paren): New name for c-unmark-<->-as-paren.
(Also renamed throughout CC Mode)

* lisp/progmodes/cc-engine.el (c-propertize-ml-string-opener):
Add missing cache invalidation.

* lisp/progmodes/cc-mode.el (c-neutralize-CPP-line): Remove
syntax-table properties from < and > as needed.
(c-put-syn-tab): Add missing cache invalidation.

(cherry picked from commit 0334b0743f83a3e69d1d3a426efbba1d2a5f2cc6)