[Bug bootstrap/51388] Configure failure to detect unsupported warning options for non-bootstrap builds (including cross builds)

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51388

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-12-02 
14:52:49 UTC ---
Since 4.4.0 we no longer warn for unrecognized -Wno- forms, thus the configure
check is broken as-is.