Convert gprs_debug.cpp to C

Change-Id: I142b870abda36950db5ff296c7c22228b0b11f55
diff --git a/src/gprs_debug.h b/src/gprs_debug.h
index b683a63..320c739 100644
--- a/src/gprs_debug.h
+++ b/src/gprs_debug.h
@@ -19,9 +19,6 @@
 extern "C" {
 #endif
 #include <osmocom/core/logging.h>
-#ifdef __cplusplus
-};
-#endif
 
 /* we used to have DBSSGP definded in each application, and applications telling
  * libosmogb which sub-system to use.  That creates problems and has been deprecated */
@@ -48,3 +45,7 @@
 };
 
 extern const struct log_info gprs_log_info;
+
+#ifdef __cplusplus
+};
+#endif