Sparc/Linux: GHC crashes

Just to let you know it looks like Sparc/Linux has bitrotted:

• http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=341797
• http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=342227

I assume this is a mangler problem, so I'll probably just switch to building it unregisterised.

Might be related to #470 (closed).