csn1: get rid of C++ specific code, compile with GCC

The implementation of CSN.1 codec was taken from Wireshark, where
it's implemented in pure C. For some reason it was mixed with C++
specific features, mostly using references in parameter
declaration. Not sure what are the benefits.

Change-Id: I56d8b7fbd2f9f4e0bdd6b09d0366fe7eb7aa327a
diff --git a/tests/rlcmac/RLCMACTest.cpp b/tests/rlcmac/RLCMACTest.cpp
index 0cc3347..a8d6217 100644
--- a/tests/rlcmac/RLCMACTest.cpp
+++ b/tests/rlcmac/RLCMACTest.cpp
@@ -24,7 +24,6 @@
 #include <cstdlib>
 #include <cstring>
 #include <assert.h>
-#include "csn1.h"
 #include "gsm_rlcmac.h"
 #include "gprs_rlcmac.h"
 #include "decoding.h"
@@ -37,6 +36,8 @@
 #include <osmocom/core/utils.h>
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/application.h>
+
+#include "csn1.h"
 }
 using namespace std;