Now using static buffers (and protecting with a semaphore) for kernel secprintf.

We have to do this because we need secure output in kmalloc.

kern/main/main.c

@@ -48,6 +48,7 @@
 #include <device.h>
 #include <syscall.h>
 #include <test.h>
+#include <kern/test161.h>
 #include <version.h>
 #include "autoconf.h"  // for pseudoconfig
 
@@ -127,6 +128,7 @@ boot(void)
 	vm_bootstrap();
 	kprintf_bootstrap();
 	thread_start_cpus();
+	test161_bootstrap();
 
 	/* Default bootfs - but ignore failure, in case emu0 doesn't exist */
 	vfs_setbootfs("emu0");