Changed fhandler_* read and raw_read methods throughout

[Christopher Faylor]

To accommodate my recent pipe changes, I've changed all of the
fhandler_* read and raw_read methods.  I've changed them to void
functions whose second parameter is both the length and the return
value.

I've done this so that if the ReadFile in raw_read succeeds but a signal
happens shortly thereafter, the number of bytes read will be available
to the caller even though the thread which did the read has been
terminated.

It's possible that I got one of the many fhandler functions wrong when I
went through making this change so if you see odd behavior this is the
place to check.

cgf