[MERGE] Wait for strace to attach before running the function we want to trace

[John Arbash Meinel]

Martin Pool wrote:
> Martin Pool has voted +1.
> Status is now: Approved
> Comment:
> That looks better; it will at least avoid any startup race.
> 
> This will possibly get jammed if strace later writes a lot of errors to
> stderr though, since we don't read any more from it.

Well, we do use proc.communicate() later.  But I think by then we would
have deadlocked.

I also wanted to remind people that "NamedTemporaryFile" doesn't allow a
third-process to access the file on Windows. I realize we probably
aren't going to try to strace() there. But whatever api is being used on
win32, it causes the file to be readable only by *this* process. (I'm
not sure what the utility of having a named file which can only be read
by self is ...)

Anyway, otherwise it seems fine.

John
=:->