Move gsm_rlcmac.cpp -> .c

Original file from wireshark.git (packet-gsm_csn1.c) is being built and
maintained as a C file. There's no real need for us to maintain it as a
C++, and doing so will make both files derive over time (as already
happened). Let's keep it as a C compiler (which btw seems to be more
strict) to make it easier to port patches back and forth wireshark.git.

Take the chance to move some declarations we added to csn1.h to be able
to build it out of wireshark. Let's keep those in a separate header file
to ease looking for differences.

Change-Id: I818a8ae947f002d35142f9f5473454cfd80e1830
diff --git a/src/csn1.h b/src/csn1.h
index 50cd9ef..a637d57 100644
--- a/src/csn1.h
+++ b/src/csn1.h
@@ -29,9 +29,7 @@
 #define _PACKET_CSN1_H_
 
 #include <osmocom/core/bitvec.h>
-
-#define MIN(a,b) (((a)<(b))?(a):(b))
-//#define max(a,b) (((a)>(b))?(a):(b))
+#include "wireshark_compat.h"
 
 /* Error codes */
 #define  CSN_OK                               0
@@ -46,17 +44,6 @@
 #define  CSN_ERROR_MESSAGE_TOO_LONG          -9
 #define  CSN_ERROR_                         -10
 
-#define FALSE (0)
-#define TRUE  (1)
-typedef signed int gint32;
-typedef signed short gint16;
-typedef int gint;
-typedef unsigned int guint;
-typedef gint gboolean;
-typedef unsigned char guint8;
-typedef unsigned short guint16;
-typedef unsigned int guint32;
-typedef unsigned long guint64;
 /* CallBack return status */
 typedef gint16 CSN_CallBackStatus_t;