[Patch] Fix ac_c99_complex configury

[Paolo Carlini]

Gabriel Dos Reis wrote:

>Old iostream members refer to the classic iostreams,
>i.e. <iostream.h>.  Thereis no doubt about it :-)
>  
>
Agreed, you are using the smiley, but I'd like to see a bit of
substantive evidence for this interpretation.

>The reason for removing complex.h is that it leads to real clashes in
>semantics with respect to C99 and we don't really need it.  I have not
>seen similar reasons for other cases.  That is a sound rationale:  If it
>won't break don't fix it.  <complex.h> breaks; others don't pause
>maintainer problems we know of.  
>
Then, maybe we should find a way to solve the problems themselves. For
instance, AFAIK, ICC/Dinkum used to provide a set of backward/ headers,
among which <complex.h> and <algobase.h> and <hash_map.h>, and so on.
Maybe they figured out a way to solve (or work around) those problems,
preferable to removing just a subset of the headers which we don't
""like"" :-)

Paolo.