[tuples] pass_ch is causing bootstrap problems on 64 bit hosts

[Diego Novillo]

Zdenek,

I can't bootstrap the tuples branch on 64bit hosts because pass_ch is 
miscompiling stage2/ifcvt.o and stage2/df-scan.o.  This causes a 
segmentation fault while compiling 32/libgcc/bid128_fma.o.

By disabling pass_ch I can get past that failure.  Would you have time 
to check it out?


Thanks.  Diego.