[util] Replace kutil with util

Now that kutil has no kernel-specific code in it anymore, it can
actually be linked to by anything, so I'm renaming it 'util'.

Also, I've tried to unify the way that the system libraries from
src/libraries are #included using <> instead of "".

Other small change: util::bip_buffer got a spinlock to guard against
state corruption.

src/kernel/objects/kobject.h

@@ -2,10 +2,10 @@
 /// \file kobject.h
 /// Definition of base type for user-interactable kernel objects
 
-#include "j6/errors.h"
-#include "j6/signals.h"
-#include "j6/types.h"
-#include "kutil/vector.h"
+#include <j6/errors.h>
+#include <j6/signals.h>
+#include <j6/types.h>
+#include <util/vector.h>
 
 class thread;
 
@@ -17,7 +17,7 @@ public:
     enum class type : uint16_t
     {
 #define OBJECT_TYPE( name, val ) name = val,
-#include "j6/tables/object_types.inc"
+#include <j6/tables/object_types.inc>
 #undef OBJECT_TYPE
 
         max
@@ -96,5 +96,5 @@ private:
     uint16_t m_handle_count;
 
 protected:
-    kutil::vector<thread*> m_blocked_threads;
+    util::vector<thread*> m_blocked_threads;
 };