Variables starting with `z' in osfmk/kern

• zdata osfmk/kern/zalloc.c:218
• zdata_size osfmk/kern/zalloc.c:219
• zone_gc_last_tick osfmk/kern/zalloc.c:1278
• zone_gc_max_rate osfmk/kern/zalloc.c:1279
• zone_labels osfmk/kern/zalloc.c:1449
• zone_page_table osfmk/kern/zalloc.c:161