Use the right appendStringInfoVA interface

pgut version renamed to avoid confusion with the server version.

(I wonder why there is such a duplication of interfaces and
implementations there though...)

lib/pgut/pgut-spi.c

@@ -29,11 +29,20 @@ termStringInfo(StringInfo str)
 static void
 appendStringInfoVA_s(StringInfo str, const char *fmt, va_list args)
 {
+#if PG_VERSION_NUM >= 90400
+	int needed;
+	while ((needed = appendStringInfoVA(str, fmt, args)) > 0)
+	{
+		/* Double the buffer size and try again. */
+		enlargeStringInfo(str, needed);
+	}
+#else
 	while (!appendStringInfoVA(str, fmt, args))
 	{
 		/* Double the buffer size and try again. */
 		enlargeStringInfo(str, str->maxlen);
 	}
+#endif
 }
 
 /* simple execute */