More undocumented performance issues with dump

[Ian! D. Allen [CGL]]

> I guess there's something dump can figure out from the file name that
> it can't figure out with fstat() on the open device.  Too bad.
> Better not have any non-standard names for your tapes, I guess.

This was wrong.  Ultrix dump assumes that any output to stdout is to a
pipe; it doesn't do the same stat() [fstat()] tests to determine device
type that it does when you give the file name on the command line.
-- 
-IAN! (Ian! D. Allen) idallen at watcgl.uwaterloo.ca idallen at watcgl.waterloo.edu
 [129.97.128.64]  Computer Graphics Lab/University of Waterloo/Ontario/Canada