- SERENITY_ROOT is being kept around for compatibility reasons, and will
be removed gradually
- SERENITY_INSTALL_ROOT points to DESTDIR but will be preferred over
that in the future
- SERENITY_SOURCE_DIR points to the root folder of the repository. Let's
keep the root terminology in the directory structure sort of sense out
of here
install-ports copys the necessary files from Ports/ to /usr/Ports. Also
refactor the compiler and destiation variables from .port_include.sh
into .hosted_defs.sh. .hosted_defs.sh does not exists when ports are
built in serenity