* include/ipexport.h: Add missing `extern "C"' directives.

* include/iphlpapi.h: Ditto.
        * include/iprtrmib.h: Ditto.
        * include/iptypes.h: Ditto.

winsup/w32api/include/ipexport.h

@@ -1,6 +1,10 @@
 #ifndef _IPEXPORT_H_
 #define _IPEXPORT_H_
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #ifndef ANY_SIZE
 #define ANY_SIZE 1
 #endif
@@ -19,4 +23,8 @@ typedef struct {
   IP_ADAPTER_INDEX_MAP Adapter[ANY_SIZE];
 } IP_INTERFACE_INFO, *PIP_INTERFACE_INFO;
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _IPEXPORT_H_ */