Handle "/"s more accurately in test for virtual semicolons (AWK Mode).

Handle "/"s more accurately in test for virtual semicolons (AWK Mode).

* progmodes/cc-awk.el (c-awk-one-line-possibly-open-string-re)
(c-awk-regexp-one-line-possibly-open-char-list-re)
(c-awk-one-line-possibly-open-regexp-re)
(c-awk-one-line-non-syn-ws*-re): Remove.
(c-awk-possibly-open-string-re, c-awk-non-/-syn-ws*-re)
(c-awk-space*-/-re, c-awk-space*-regexp-/-re)
(c-awk-space*-unclosed-regexp-/-re): New constants.
(c-awk-at-vsemi-p): Reformulate better to recognize "/"s which
aren't regexp delimiters.

* progmodes/cc-engine.el (c-crosses-statement-barrier-p): Add in
handling for a rare situation in AWK Mode involving unterminated
strings/regexps.