Amend to fontify /regexp/s in actions correctly.

Amend to fontify /regexp/s in actions correctly.
cc-awk.el (c-awk-harmless-char-re, c-awk-harmless-string*-re):
(c-awk-harmless-string*-here-re): braces, parens and semicolons are no
longer included.
(c-awk-harmless-line-char-re, c-awk-harmless-line-string*-re): What used
to be these variables without "-line" in the name.
(c-awk-neutral-re): { is no longer neutral.  Escaped newlines now are.
(c-awk-non-arith-op-bra-re): Now also matches {.
(c-awk-pre-exp-alphanum-kwd-re): New regexp to match "print", "return",
and "case".
(c-awk-kwd-regexp-sign-re): New, to match "print", etc., followed by /.
(c-awk-syntax-tablify-/): Check special cases "print /re/", etc.
(c-awk-set-syntax-table-properties): Extend FSM to handle {,},(,),;.