'FILE' undefined on -DEVEL?

[walt <wa1ter@xxxxxxxxxxxxx>]

While trying to build a pkgsrc package, the configure step failed because this
code won't compile on DFly:

 #include <sys/types.h>
 #include <inttypes.h>
 #include <stdint.h>
 #include <stddef.h>
 #include <unistd.h>
 #include <stdio.h>

 typedef FILE ac__type_new_;
 int
 main ()
 {
 if ((ac__type_new_ *) 0)
   return 0;
 if (sizeof (ac__type_new_))
   return 0;
   ;
   return 0;
 }

AFAICT, the reason is that FILE is undefined, or wrongly defined.  The same
code compiles on the other BSDs and linux, so we are different somehow.

Is this by intention, and why?

Thanks.