Add a control-flow test with a loop and multiple translations for a srckey

Summary: This test exercises some corner cases that were causing assertion
failures in dbgo (now fixed).  It never quite repro'ed the exact bug I was
seeing, but it seems like a reasonable stress test to have in the tree.

Reviewed By: @alexmalyshev

Differential Revision: D1403027
Log unit when failing the fromLoad assertion in refcount opts

Summary: This assert popped up on a diff last night but it seems somewhat rare,
so let's print the unit to debug it when it does happen.

Reviewed By: @ottoni

Differential Revision: D1402862
Fixing out of tree build, cmake

Summary: Closes #3023
Fixes #2922

Reviewed By: @ptarjan

Differential Revision: D1400227

Pulled By: @JoelMarcey