Bug#582774: seed FTBFS on ia64

[peter green]

 From looking at http://wiki.debian.org/ArchitectureSpecificsMemo I have 
a suspision that ia64 needs to be added to the list of architectures 
needing aligned accesses in webkit like sparc was recently. However I 
have no way of testing if this fixes the build failure nor any 
particular interest in fixing it myself (I only looked at the sparc 
issue because it was getting in the way of a port I do care about.