systemd: define strerror() in sd-adapt header to nm_strerror_native()

Systemd uses strerror() extensively. Patch the function to use the thread-safe
nm_strerror_native().

shared/systemd/sd-adapt-shared/nm-sd-adapt-shared.h

@@ -27,6 +27,11 @@
 
 /*****************************************************************************/
 
+/* strerror() is not thread-safe. Patch systemd-sources via a define. */
+#define strerror(errsv) nm_strerror_native (errsv)
+
+/*****************************************************************************/
+
 static inline NMLogLevel
 _slog_level_to_nm (int slevel)
 {

src/tests/test-systemd.c

@@ -80,6 +80,12 @@ nm_logging_setup (const char  *level,
 	return TRUE;
 }
 
+const char *
+nm_strerror_native (int errsv)
+{
+	return g_strerror (errsv);
+}
+
 /*****************************************************************************/
 
 static void