iarray_init - initialize iarray data structure

       iarray_init  initializes  an  iarray so that it can hold elements of size elemsize.  iarray_init does not
       actually allocate anything, so it can not fail.

       iarray_init - initialize iarray data structure

iarray_allocate(3), iarray_get(3), iarray_free(3)

                                                                                                  iarray_init(3)

#include<libowfat/iarray.h>

       void iarray_init(array* x, size_t elemsize);

         iarray x;
         int64 pos;
         t* p = iarray_init(&x,sizeof(element));