Improve zombie termination script
Improve zombie termination script

The previous version would not terminate if
the program being invoked terminated. The
new version addresses this at the cost of
starting a background process for stdin
reading.

Closes #9171.

kelvinst/elixir,ggcampinho/elixir,lexmag/elixir,joshprice/elixir,michalmuskala/elixir,kelvinst/elixir,lexmag/elixir,pedrosnk/elixir,ggcampinho/elixir,kimshrier/elixir,pedrosnk/elixir,kimshrier/elixir,elixir-lang/elixir