Limit the amount of bytes read into char units[255], bug 278186.

--- htmldoc/util.cxx.orig	2009-07-17 19:28:53.000000000 +0200
+++ htmldoc/util.cxx	2009-07-17 19:29:07.000000000 +0200
@@ -484,7 +484,7 @@
     PageWidth  = 595;
     PageLength = 792;
   }
-  else if (sscanf(size, "%fx%f%s", &width, &length, units) >= 2)
+  else if (sscanf(size, "%fx%f%254s", &width, &length, units) >= 2)
   {
    /*
     * Custom size...