CC-Mode: Remove unneeded backslashes from doc strings and regular expressions

CC-Mode: Remove unneeded backslashes from doc strings and regular expressions

Also make miscellaneous amendments.

* lisp/progmodes/cc-align.el, lisp/progmodes/cc-cmds.el
* lisp/progmodes/cc-defs.el, lisp/progmodes/cc-engine.el
* lisp/progmodes/cc-langs.el, lisp/progmodes/cc-vars.el: Remove lots of
unneeded backslashes.

* lisp/progmodes/cc-langs.el (c-string-innards-re-alist): Remove redundant
"\\|\r" from regular expression.

* lisp/progmodes/cc-mode.el (c-make-mode-syntax-table): Correct the name of
the hook normal-erase-is-backspace-MODE-hook from a non-existant hook name.