Fix indentation/fontification of Java enum with "implements".

Fix indentation/fontification of Java enum with "implements".

* progmodes/cc-langs.el (c-postfix-decl-spec-key): New variable, a
regexp which matches "implements", etc., in Java.
* progmodes/cc-engine.el (c-inside-bracelist-p): Check for extra
specifier clauses coming after "enum".
* progmodes/cc-fonts.el (c-font-lock-declarations)
(c-font-lock-enum-tail): Check for extra specifier clauses coming
after "enum".