Fix the assumption in the propagate_const test about local layout
Fix the assumption in the propagate_const test about local layout

Summary: [Folly] Fix the assumption in the `propagate_const` test about local layout.

Reviewed By: aary

Differential Revision: D6624962

fbshipit-source-id: 6871dc20f2b5ec2d1a86f520030c7cda8a225958

facebook/folly,rklabs/folly,facebook/folly,rklabs/folly,facebook/folly,rklabs/folly,facebook/folly,rklabs/folly,rklabs/folly,facebook/folly