Bug on macOS

[schweitzpgi]

The test for #4098 fails inexplicably on the macOS build. Since I have no way to debug that, I am going to mark the test unsupported to get the PR committed.

It looks like the greedy rewriter is terminating too early. The algorithm for struq types is to eliminate the quake.alloca of the struq and replace it with a set of alloca operations, one for each member. At that point, the greedy rewriter should recurse and expand the alloca veq into a set of alloca ref operations. The failure is that recursive step fails.

Need someone to debug this on a Mac.