Fix passing MoveWrapper into lambdas

Fix passing MoveWrapper into lambdas

Summary:
GCC can't compile code that passes a MoveWrapper into a lambda
in some cases. For example if the capture list has
[someConstObject, myMoveWrapper], gcc 4.7 fails. This specific case
works with gcc 4.8, but other cases (e.g. [this, myMoveWrapper]) still
fail.

This diff is a hack that makes code like that compile. It can be
removed, along with MoveWrapper itself once we move to C++14 with its
extended lambda syntax.

Test Plan: fbmake

Reviewed By: hans@fb.com

FB internal diff: D1032585