Fix coverage build failure
Fix coverage build failure

Summary: [Thrift] Fix coverage build failure - not sure what the root cause of the failure is in the coverage tools, but anyway this version is net better.

Reviewed By: Mizuchi

Differential Revision: D24696395

fbshipit-source-id: c8b6a09da2c28822c55fa4f61e4ee195404ce0b1

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift