[PATCH] Fix PR32586, restore combining of conversions in SCCVN

[Eric Botcazou]

> We seem to have some wacky latent problem somewhere.  Bootstrap fails
> again.  My #1 bet is always aliasing (it has been easy lately to
> hide/expose bugs there because partitioning is so volatile).

I can bootstrap C/C++/Ada on i586 but Ada EH is terminally broken there: 
ada/raise-gcc is miscompiled at -O2 (but not at -O2 -fno-strict-aliasing).

-- 
Eric Botcazou