Handle message truncation, zombies, sigchld handling.
Changes to get verbose compiler output down to a manageable
size. Added option, -mN to limit output to N kb. Default
is to capture all compiler generated output. Added this
option to ignore massive compiler diagnostic outout
associated with some compilers. With this change, I can
increase the nightly timeout to longer than 300 seconds to
give some slower compilers a change to finish compiling.