AROS: 32/64-bit fix field alignment for unit conunit

Make sure AROS' record structures are C-packed.

packages/arosunits/src/conunit.pas

@@ -40,7 +40,7 @@ const
 
 
 type
-  {$PACKRECORDS 2}
+  {$PACKRECORDS C}
   PConUnit = ^TConUnit;
   TConUnit = record
     cu_MP: TMsgPort;