message: fuzz: http_request workaround for libevent < 2.1.1
  Before libevent 2.1.1, internal functions names didn't end with an underscore.
diff: #include <test/fuzz/util.h>
  #include <event2/buffer.h>
  +#include <event2/event.h>
  #include <event2/http.h>
  #include <event2/http_struct.h>
  #include <string>
  #include <vector>
  +// workaround for libevent versions before 2.1.1,
  +// when internal functions didn't have underscores at the end
  +#if LIBEVENT_VERSION_NUMBER < 0x02010100
  +extern "C" int evhttp_parse_firstline(struct evhttp_request*, struct evbuffer*);
  +extern "C" int evhttp_parse_headers(struct evhttp_request*, struct evbuffer*);
  +inline int evhttp_parse_firstline_(struct evhttp_request* r, struct evbuffer* b)
  +{
  + return evhttp_parse_firstline(r, b);
  +}
  +inline int evhttp_parse_headers_(struct evhttp_request* r, struct evbuffer* b)
  +{
  + return evhttp_parse_headers(r, b);
  +}
  +#else
  extern "C" int evhttp_parse_firstline_(struct evhttp_request*, struct evbuffer*);
  extern "C" int evhttp_parse_headers_(struct evhttp_request*, struct evbuffer*);
  +#endif
  +
  std::string RequestMethodString(HTTPRequest::RequestMethod m);
  void test_one_input(const std::vector<uint8_t>& buffer)
  