Move utilities to util/

app/tests/test_cbuf.c

@@ -1,7 +1,7 @@
 #include <assert.h>
 #include <string.h>
 
-#include "cbuf.h"
+#include "util/cbuf.h"
 
 struct int_queue CBUF(int, 32);
 

app/tests/test_queue.c

@@ -1,6 +1,6 @@
 #include <assert.h>
 
-#include <queue.h>
+#include "util/queue.h"
 
 struct foo {
     int value;

app/tests/test_strutil.c

@@ -1,7 +1,7 @@
 #include <assert.h>
 #include <string.h>
 
-#include "str_util.h"
+#include "util/str_util.h"
 
 static void test_xstrncpy_simple(void) {
     char s[] = "xxxxxxxxxx";