Spotted by Dimitry Andric: `ssh-termspeed' implementation was not taking

Spotted by Dimitry Andric: `ssh-termspeed' implementation was not taking
account of coroutines and used local variables over a crFoo. I believe the
impact was cosmetic, affecting the speeds reported in the Event Log only.

I've put the variables `ispeed' and `ospeed' in the main ssh_tag structure,
even though they're only live for a short duration; I did this rather than
create a new state struct for ssh1_protocol() (since ssh_tag already has
short-duration junk like portfwd_strptr).

[originally from svn r4272]