Work around u8path being deprecated in c++20

Author: tgoyne

test/benchmark-larger/main.cpp

@@ -163,7 +163,7 @@ int main()
                               << std::endl;
                     start = end;
                     for (size_t i = 0; i < probe_size; ++i) {
-                        sum += objects[i].get<Int>(col2);
+                        sum = sum + objects[i].get<Int>(col2);
                     }
                     end = std::chrono::steady_clock::now();
                     diff = end - start;

test/test_util_file.cpp

@@ -117,9 +117,15 @@ TEST(Utils_File_dir)
 
 TEST(Utils_File_dir_unicode)
 {
+#if __cplusplus < 202002L
     using std::filesystem::u8path;
+#else
+    auto u8path = [](const std::string& str) {
+        return std::filesystem::path(reinterpret_cast<const char8_t*>(str.c_str()));
+    };
+#endif
 
-    constexpr char all_the_unicode[] = u8"фоо-бар Λορεμ ლორემ 植物 החלל جمعت søren";
+    const char* all_the_unicode = (const char*)u8"фоо-бар Λορεμ ლორემ 植物 החלל جمعت søren";
     std::string dir_name = File::resolve(all_the_unicode, test_util::get_test_path_prefix());
 
     // Create directory