use __h_errno_location for h_errno
we do not bother making h_errno thread-local since the only interfaces
that use it are inherently non-thread-safe. but still use the
potentially-thread-local ABI to access it just to avoid lock-in.
diff --git a/include/netdb.h b/include/netdb.h
index a480d82..33b7a0a 100644
--- a/include/netdb.h
+++ b/include/netdb.h
@@ -128,7 +128,11 @@
int gethostbyaddr_r(const void *, socklen_t, int, struct hostent *, char *, size_t, struct hostent **, int *);
int getservbyport_r(int, const char *, struct servent *, char *, size_t, struct servent **);
int getservbyname_r(const char *, const char *, struct servent *, char *, size_t, struct servent **);
-extern int h_errno;
+#ifdef __GNUC__
+__attribute__((const))
+#endif
+int *__h_errno_location(void);
+#define h_errno (*__h_errno_location())
#define EAI_NODATA -5
#define EAI_ADDRFAMILY -9
#define EAI_INPROGRESS -100