First, you can safely ignore those messages. This is a known condition after the installation of Mojave (macOS 10.14) or the macOS 10.13.6+ updates.
You can try to remove them by having the OS regenerate the compatibility files (Apple uses a different library format for macOS app development but has a compatibility layer for "normal" development). To do that, set aside abt 8 minutes on a fast internet connection, open a command-line prompt (Terminal/iTerm) and do:
sudo mv /Library/Developer/CommandLineTools /Library/Developer/CommandLineTools.old
then do:
xcode-select --install
and follow the instructions and wait.
Re-try your package/source compilations and if the messages go away, you should be able to safely do:
sudo rm -rf /Library/Developer/CommandLineTools.old
but leaving that directory tree there should not do any harm (provided you have the free space to spare).