Analyze C++ method with & or && ref-qualifier as defun, not brace list

Analyze C++ method with & or && ref-qualifier as defun, not brace list

Also firm up detection of beginning of brace list in
c-looking-at-or-maybe-in-bracelist.

* lisp/progmodes/cc-engine.el (c-looking-at-or-maybe-in-bracelist): On
detection of such a ref-qualifier, set braceassignp to nil.  When this
variable has a nil value, return nil as the value of the function.  On
encountering a } when scanning backwards, recognise this as the end of a
previous construct and stop the scan.