AC_CACHE_VAL(AC_CV_NAME,
[for ac_size in 4 8 1 2 16 $2 ; do # List sizes in rough order of prevalence.
AC_TRY_COMPILE([#include "confdefs.h"
+#include <stdlib.h>
#include <sys/types.h>
$2
], [switch (0) case 0: case (sizeof ($1) == $ac_size):;], AC_CV_NAME=$ac_size)