Fix an infinite loop in C++ Mode redisplay. This was bug #47191.

Fix an infinite loop in C++ Mode redisplay.  This was bug #47191.

* lisp/progmodes/cc-defs.el (c-forward-syntactic-ws, c-backward-syntactic-ws):
When point is on the wrong side of a supplied search limit, leave point
unmoved rather than setting it to that limit.

* lisp/progmodes/cc-engine.el (c-forward-name): After scanning a template
argument list (which is not itself subject to a search limit) recalculate the
search limit starting from the end point, since these argument lists can
legitimately be long.  At each of the scanning loops, check point hasn't gone
past the limit.