only PATH and SOLARENV which is used as a trigger to call Env.Host.sh
are left...

JAVAHOME is used in an obscure test module in moz, that does not seems
to be run anyway... other than that, no trace of it
so no need to export it.

prep-work for the migration of PATH handling from set_soenv...

this variable is onyl used if you have a set of know files that should
all correctly import in filters-test