fixed build for gcc 8-9

build/CMakeLists.txt

@@ -209,6 +209,10 @@ if(WITH_THREADSANITIZER)
   endif()
 endif()
 
+if (CMAKE_COMPILER_IS_GNUCC AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 10.0 AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 8.0) # gcc 8-9
+    list(APPEND CMAKE_REQUIRED_LIBRARIES "stdc++fs")
+endif()
+
 # Use std::atomic instead of GCC builtins on macOS PowerPC:
 # For more information refer to: https://github.com/PurpleI2P/i2pd/issues/1726#issuecomment-1306335111
 # This has been fixed in Boost 1.81, nevertheless we retain the setting for the sake of compatibility.