[Bug driver/47547] WHOPR, can't use /dev/null as an output file

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47547

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2011-01-31 14:32:34 UTC ---
(In reply to comment #1)
> 
> I think HJ caused this (the -dumpdir / -dumpbase flags are bogus), non-LTO
> does not use -dumpdir, lto-wrapper.c is what sets that flag (I don't
> remember why -dumpdir is used at all - HJ?).

It is for PR 41564.