[ANNOUNCE] Changes to the build system: Env.Host.sh is dead so is the need to source the environment

[Tor Lillqvist]

> However, running git `grep set_soenv1`, shows many remnants of
> set_soenv.*, just in case someone knowledgeable about the build system
> wants to check them.

At least the set_soenv.stamp file is still presumably useful (created
by configure and checked in one place), even if its name now is a bit
meaningless if you don't know history.

--tml