reify blocks export and play mode on windows

[timsgardner]

Code with reify seems to block Windows export and play mode after AOT.

Oddly, the use of reify in clojure.core.reducers does not seem to trigger this problem.

To replicate:

• Define a function that uses reify in a user namespace.
• AOT.
• Prepare for export and build, or enter play mode.

An error will be thrown.

Workaround for this at e7e50af, which just removes all use of reify from our code, but we need to fix the underlying problem.

The new work on MAGIC will hopefully fix this issue.