Clear db_active in boot() so that one can call the boot function (as well

as use the panic command) w/o having to manually clear db_active first
to avoid the db_error() in mi_switch().

sys/kern/kern_shutdown.c

@@ -67,6 +67,9 @@
 #include <machine/md_var.h>
 
 #include <sys/signalvar.h>
+#ifdef DDB
+#include <ddb/ddb.h>
+#endif
 
 #ifndef PANIC_REBOOT_WAIT_TIME
 #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
@@ -208,6 +211,11 @@ boot(int howto)
 	/* collect extra flags that shutdown_nice might have set */
 	howto |= shutdown_howto;
 
+#ifdef DDB
+	/* We are out of the debugger now. */
+	db_active = 0;
+#endif
+
 #ifdef SMP
 	if (smp_active)
 		printf("boot() called on cpu#%d\n", PCPU_GET(cpuid));