[Patch] Fix ac_c99_complex configury

[Gabriel Dos Reis]

Benjamin Kosnik <bkoz@redhat.com> writes:

| Hey, I think we can just do this, huh?

Hmm, I'm confused.  But, yes, I agree we may probably stop 
<complex.h> since it now means something different in C99.  
Hmm.  C++ + C99 == mess.
:-(

-- Gaby