perf_counter tools: move helper library to util/*

Clean up the top level directory a bit by moving all the helper libraries
to util/*.[ch].

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/perf_counter/builtin-top.c b/Documentation/perf_counter/builtin-top.c
index 98e8690..dea016f 100644
--- a/Documentation/perf_counter/builtin-top.c
+++ b/Documentation/perf_counter/builtin-top.c
@@ -42,7 +42,7 @@
   * Released under the GPL v2. (and only v2, not any later version)
   */
 
-#include "util.h"
+#include "util/util.h"
 
 #include <getopt.h>
 #include <assert.h>