a few upgrades for the HttpServer example (#955)

examples/helpers/AsyncFileStreamer.h

@@ -1,4 +1,4 @@
-#include <experimental/filesystem>
+#include <filesystem>
 
 struct AsyncFileStreamer {
 
@@ -12,7 +12,7 @@ struct AsyncFileStreamer {
 
     void updateRootCache() {
         // todo: if the root folder changes, we want to reload the cache
-        for(auto &p : std::experimental::filesystem::recursive_directory_iterator(root)) {
+        for(auto &p : std::filesystem::recursive_directory_iterator(root)) {
             std::string url = p.path().string().substr(root.length());
             if (url == "/index.html") {
                 url = "/";
@@ -38,7 +38,7 @@ struct AsyncFileStreamer {
     static void streamFile(uWS::HttpResponse<SSL> *res, AsyncFileReader *asyncFileReader) {
         /* Peek from cache */
         std::string_view chunk = asyncFileReader->peek(res->getWriteOffset());
-        if (!chunk.length() || res->tryEnd(chunk, asyncFileReader->getFileSize())) {
+        if (!chunk.length() || res->tryEnd(chunk, asyncFileReader->getFileSize()).first) {
             /* Request new chunk */
             // todo: we need to abort this callback if peer closed!
             // this also means Loop::defer needs to support aborting (functions should embedd an atomic boolean abort or something)