configure.ac: Fix breakage caused by -Werror=unused-variable

[Alexandre Julliard]

Daniel Santos <daniel.santos at pobox.com> writes:

> On 09/07/2015 04:53 AM, Alexandre Julliard wrote:
>> Daniel Santos <daniel.santos at pobox.com> writes:
>>
>>> When configuring with CFLAGS="-Wunused-variable -Werror", the configure
>>> test for HAVE_PNG_SET_EXPAND_GRAY_1_2_4_TO_8 fails with unused variable.
>> Running configure with -Werror is not a good idea. Is there a particular
>> reason why you need this?
>>
> Not for configure in particular, but for the build I prefer to have
> the highest level of warnings enabled (that won't produce spam) and
> I've found -Werror a good way to make sure that none slip past me.

It would be better to specify CFLAGS at make time. Making configure
-Werror proof is not possible given the wide variety of environments it
needs to support.

-- 
Alexandre Julliard
julliard at winehq.org