Reproduction steps:
1. Open the attached project;
2. Check if Scripting Backend is set to IL2CPP;
3. Build the project on a device;
4. Check the built symbols.zip file;

Actual result: the built symbols.zip file is empty.
Expected result: the built symbols.zip file should contain information inside.

Reproducible with: 5.6.2f1, 5.6.3f1, 2017.1.0p4, 2017.2.0b8

Note: when the project is built with 5.6.1f1 and earlier versions, the symbols.zip file is not built at all.

The issue is fixed in 2017.3.0a4