Disable -Wdiv-by-zero for some tests in stdio-common/tst-unlockedio.c

[Joseph Myers]

On Tue, 2 Dec 2014, Roland McGrath wrote:

> OK

Note that this can't go in without the macro definitions in 
<https://sourceware.org/ml/libc-alpha/2014-11/msg00736.html> - if the 
macros are OK but the use for scanf tests needs further consideration, I'd 
welcome review of the macro definitions on their own to unblock other 
changes using them (including warning avoidance using the macros in 
architecture-specific files).

-- 
Joseph S. Myers
joseph@codesourcery.com