Don't use -Wno-error=undef

[Andreas Schwab]

Joseph Myers <joseph@codesourcery.com> writes:

> Tested for x86_64 and x86.  If people see build or test errors
> resulting from this on other architectures, they should fix those as
> usual.

That's not how things should work.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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