Milter-greylist

> > On my system the resolv.h does not contain the following statement:
> >
> > typedef struct __res_state *res_state;
> >
> > So I have only __res_state and not res_state.
> 
> You could add an autoconf test to look for res_state, and define a
> HAVE_RES_STATE, then:
> 
> #ifndef HAVE_RES_STATE
> typedef struct __res_state *res_state;
> #endif
> 

I am not an autoconf expert.
May anybody help to write the test for the existence of res_state?