Unbreak x86-64 (and others ;) bootstrap

[Jan Hubicka]

> Hi,
> I am just testing the attached patch that appears to fix all the
> bootstrap problems reproduced on x86-64.  First problem is the invalid
> node sharing caused by fold, second problem is prepare_decl_rtl puting
> register into DECL being referenced via addressof making RTL expansion
> to fail, third problem is use of frontend specific unsigned_type_node
> that is not initialized by Java, fourth problem is broken loop debug
> output.
> 
> If everything works on x86-64-unknown-linux, I will commit it to unbreak
> the bootstraps.

Bootstrap/regtest on x86-64-unknown-linux passed for me, so I am now
moving to ppc target to see if it works.  Let me know if you notice any
further breakage.

Honza