Don't include <stddef.h> "For offsetof". This is not even wrong in

-current, since offsetof() is defined a header under /sys so that
system sources don't need to have this wrong include.

This bug was only detected because my version of <stddef.h> has some
spelling fixes (s/field/member/g) and gcc is now sensitive to the spelling
of arg names in macros as required by standards (ISO C90 6.8.3...).

sys/dev/iir/iir.c

@@ -54,8 +54,6 @@
 #include <sys/kernel.h>
 #include <sys/bus.h>
 
-#include <stddef.h>     /* For offsetof */
-
 #include <machine/bus_memio.h>
 #include <machine/bus_pio.h>
 #include <machine/bus.h>