remove pcu own bitvector implementation

The osmocore bitvec is exact the same, but use a pointer instead of
a reference.

Change-Id: Id8f797631d89aa12b6e48efb2dc153a3e2f059f7
diff --git a/src/csn1.h b/src/csn1.h
index 96f7558..3f5b849 100644
--- a/src/csn1.h
+++ b/src/csn1.h
@@ -25,7 +25,10 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */
 
-#include <bitvector.h>
+extern "C" {
+#include <osmocom/core/bitvec.h>
+}
+
 #include <iostream>
 #include <cstdlib>
 #ifndef _PACKET_CSN1_H_