Backward compatibility break of mysql_config

The shell script bin/mysql_config should provide information on how MySQL/MariaDB has been deployed.
For example if you have copied the Linux binaries directly on /opt/mariadb of your system, a call to /opt/mariadb/bin/mysql_config --include will tell you that you should add -I/opt/mariadb/include/mysql -I/opt/mariadb/include/mysql/.. to any compilation that uses the MySQL/MariaDb headers.
This is now broken by MDEV-13836 and commit a75884e.
In this development it was chosen to match the outputs of mariadb_config and mysql_confg. But mariadb_config doesn't care about where the files are located. It only uses the compilation options of MariaDB. So today if you download the binary packages you will get
-I/usr/local/mysql/include/mysql -I/usr/local/mysql/include/mysql/mysql no matter where you choose to deploy MariaDB on your system.
For me, this is a major backward compatibility issue. We should revert to give the choice between mysql_config and mariadb_config with their different behavior.