[6.0.0] Plumb through the testing library version into a function instead of a C++ macro. #650
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Explanation: Correctly sets the testing library version (it was failing to set on the Swift side.)
Scope: Building with CMake
Issue: N/A
Original PR: #648
Risk: Low
Testing: Built a toolchain and verified the string was ingested all the way through.
Reviewer: @grynspan @briancroom