swift234

fixed: specialization of reabstraction thunk in CapturePropagation results in broken code.

CapturePropagation could produce specialized reabstraction thunks with the same symbol name
in different files. The effect was that the wrong thunk could be called.

Fixed by setting the linkage to private.

This fixes <rdar://problem/18906781> Swift compiler produces incorrect code when in Release mode



Swift SVN r23367