buf_init
extern void buf_init PROTO ((struct Buf * buf, size_t elem_size));
buf_init(&tmpbuf, sizeof(char));
buf_init(&userdef_buf, sizeof(char)); /* one long string */
buf_init(&defs_buf, sizeof(char *)); /* list of strings */
buf_init(&yydmap_buf, sizeof(char)); /* one long string */
buf_init(&top_buf, sizeof(char)); /* one long string */
buf_init(&m4defs_buf, sizeof(char *));