sh64 support

[Joern RENNECKE]

My simulator now segfaults for every single execution test built with 
mainline; when I try gdb, it also segfaults,
somewhere in the dwarf handling code.
Unless someone comes up with a viable concept how to maintain sh64 
support in gcc, I think we have to deprecate
it now, since at the time of the gcc 4.3 release it can be expected to 
have bitrotted too much to be more useful than
or even as useful as a vintage release.