Fix memory leak on error path in md5_printf

components/esp_http_client/lib/http_auth.c

@@ -43,6 +43,7 @@ static int md5_printf(char *md, const char *fmt, ...)
     va_start(ap, fmt);
     len = vasprintf((char **)&buf, fmt, ap);
     if (buf == NULL) {
+        va_end(ap);
         return ESP_FAIL;
     }