Platform tweaks for h_errno

ext/lwip/src/api/netdb.c

@@ -58,7 +58,7 @@ struct gethostbyname_r_helper {
 
 /** h_errno is exported in netdb.h for access by applications. */
 #if LWIP_DNS_API_DECLARE_H_ERRNO
-int h_errno;
+//int h_errno;
 #endif /* LWIP_DNS_API_DECLARE_H_ERRNO */
 
 /** define "hostent" variables storage: 0 if we use a static (but unprotected)

ext/lwip/src/include/lwip/netdb.h

@@ -116,7 +116,13 @@ struct addrinfo {
 
 #if LWIP_DNS_API_DECLARE_H_ERRNO
 /* application accessible error code set by the DNS API functions */
+#if defined(__APPLE__)
 extern int h_errno;
+#endif
+#if defined(__linux__)
+extern __thread int h_errno;
+#endif
+
 #endif /* LWIP_DNS_API_DECLARE_H_ERRNO*/
 
 struct hostent *lwip_gethostbyname(const char *name);