Ractor verification requires storing the ractor id in the top 32 bits of
the object header.  Unfortunately 32 bit machines only have 32 bits in
the object header.  The verification code has a 32 bit left shift which
doesn't work on i686 and will clobber existing flags.

This commit disables the verification code on i686 since i686 will crash
if it's enabled.

Co-Authored-By: John Hawthorn <john@hawthorn.email>
Co-Authored-By: Jemma Issroff <jemmaissroff@gmail.com>