non-root install my.sql default location support

Customer request enhancement for non-root install and the default setup for my.cnf

1. MYSQL_HOME is not defined - appears to be much more useful for non-root installs for apps to locate the my.cnf file

2. When a my.cnf file cannot be located, the client tries to use a bogus internal default socket 'db/mysql.sock' file, which does not exist.

3. software support the default /etc/my.cnf