hardcoded /tmp instead of TMPDIR

[Pavel Roskin]

Hello!

Again replying to myself :-)

> Another solution - use some predefined token on stdout.  In other words, 
> replace pwd with something like:
> 
> echo "Attention mc pid 1923: "; pwd; echo " mc pid 1923 done"

Better yet - output the working directory after the "kill", not before,
and use stdout.  The first line from the subshell stdout after SIGCONT
will be the working directory.  The rest will be the prompt.

This would eliminate all pipes for all subshells.  feed_subshell() would
have to check for SIGCHLD in the loop, instead of relying on the pipe
output as the sign that the subshell has completed the command.

The prompt will be loaded when it's ready, not when load_prompt() requests 
it.  That would fix some artifacts too.

Unfortunately, the amount of the requires changes make it unrealistic to
implement this proposal before 4.6.0.

-- 
Regards,
Pavel Roskin