libutils: hide SharedBuffer by moving SharedBuffer.h to the implementation directory

Some methods in header files of classes using SharedBuffer need
to be moved to the implementation files accordingly

Change-Id: I891f3ace2b940ab219e4e449040bfed71c0547db
diff --git a/libutils/VectorImpl.cpp b/libutils/VectorImpl.cpp
index 2f770f5..2ac158b 100644
--- a/libutils/VectorImpl.cpp
+++ b/libutils/VectorImpl.cpp
@@ -23,9 +23,10 @@
 #include <cutils/log.h>
 
 #include <utils/Errors.h>
-#include <utils/SharedBuffer.h>
 #include <utils/VectorImpl.h>
 
+#include "SharedBuffer.h"
+
 /*****************************************************************************/