Method set_posix_syntax

extern/re2/re2/re2.h:677–677

    bool posix_syntax() const { return posix_syntax_; }
    void set_posix_syntax(bool b) { posix_syntax_ = b; }

    bool longest_match() const { return longest_match_; }
    void set_longest_match(bool b) { longest_match_ = b; }