Ben Gamari authored Feb 14, 2017 and Ben Gamari committed Feb 14, 2017

While this apparently didn't matter on Linux, the OS X toolchain seems
to treat local and external symbols differently during linking. Namely,
the linker assumes that an external symbol marks the beginning of a new,
unused procedure, and consequently drops it.

Fixes regression introduced in D2741.

Test Plan: `debug` testcase on OS X

Reviewers: austin, simonmar, rwbarton

Reviewed By: rwbarton

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3135