Disable flow control for beam started via run_erl

[Jonas Falkevik]

Hi,
We had some problem with accidentally hitting ctrl-s (too close to ctrl-d)
when detaching from the erlang shell attached with to_erl.
This if not noticed and neutralized by ctrl-q could make the beam block
which is not desired behaviour for a live system.

This patch makes it possible to disable the feature of blocking the beam
with ctrl-s.

A new environment variable is introduced RUN_ERL_DISABLE_FLOWCNTRL which
should be set before you run run_erl.

git fetch git://github.com/falkevik/otp.gitopt_disable_of_flowctrl_for_run_erl_shell


Regards,
Jonas Falkevik