Warn users about requirement of having linprocfs mounted in order to
start native JDK port build. linprocfs mounted become pre-requisite of
build after Linux SUN JDK port was updated to 1.4.2.
Add run-time (pre-build) check for linprocfs mounted as well.
Bump space requirements note about disk space required for build of
whole JDK 1.4.1 port and package to more appropriate value (as reported
by many people).