Fixes to chunked support when pipelining

src/sock.c

@@ -650,8 +650,13 @@ void mg_mgr_poll(struct mg_mgr *mgr, int ms) {
   mg_timer_poll(&mgr->timers, now);
 
   for (c = mgr->conns; c != NULL; c = tmp) {
+    bool is_resp = c->is_resp;
     tmp = c->next;
     mg_call(c, MG_EV_POLL, &now);
+    if (is_resp && !c->is_resp) {
+      struct mg_str fake = mg_str_n("", 0);
+      mg_call(c, MG_EV_READ, &fake);
+    }
     MG_VERBOSE(("%lu %c%c %c%c%c%c%c", c->id, c->is_readable ? 'r' : '-',
                 c->is_writable ? 'w' : '-', c->is_tls ? 'T' : 't',
                 c->is_connecting ? 'C' : 'c', c->is_tls_hs ? 'H' : 'h',