[Patch] Fix ac_c99_complex configury

[Paolo Carlini]

Gabriel Dos Reis wrote:

>Paolo Carlini <pcarlini@suse.de> writes:
>
>| Another, more serious, tought I entertained during the last weeks,
>| actually, is whether we could *finally* remove the include/backward
>| stuff! I believe that for 4.1 would be absolutely *correct* wrt our
>| deprecation/removal policy.
>
>In theory it would be in line with our policy; however in practice it
>would be a disaster.  This stuff is even described in the C++ standard
>(under the deprecated heading I agree) and there are still people
>using it.
>
Are you *really* *sure* the standard describes such headers?!? I don't
think so.

This just out of curiosity, to be clear, no problem at all with me!

Paolo.