cmUdpNet.h: Added extern "C" {} wrapper.

cmUdpNet.h

@@ -1,6 +1,10 @@
 #ifndef cmUdpNet_h
 #define cmUdpNet_h
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /*
   A cmUdpNet is a wrapper around a single cmUdpPort. This object
   maintains an array of remote nodes which map application defined
@@ -128,4 +132,8 @@ void     cmUdpNetReport( cmUdpNetH_t h, cmRpt_t* rpt );
 
 cmRC_t cmUdpNetTest( cmCtx_t* ctx, int argc, char* argv[] );
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif