Defines starting with `d' in osfmk/kern

• DB_HALT osfmk/kern/debug.h:60
• DB_KDB osfmk/kern/debug.h:64
• DB_KPRT osfmk/kern/debug.h:63
• DB_NMI osfmk/kern/debug.h:62
• DB_PRT osfmk/kern/debug.h:61
• DECREMENTER_TIMEOUT osfmk/kern/lock.c:1017
• DEFAULT_PREEMPTION_RATE osfmk/kern/sched_prim.c:107
• DEPRESSPRI osfmk/kern/sched.h:98
• DISPOSITION_MASK osfmk/kern/subsystem.c:452