Reproduction steps:
1) Open user's attached project
2) Make sure Scripting Backend is set to IL2CPP
3) Try to build project
-- Notice that Unity fails at building this project with IL2CPP:

Exception: E:\Unity5.5.0p3\Editor\Data\Tools/UnusedByteCodeStripper2/UnusedBytecodeStripper2.exe did not run properly!
UnityEditorInternal.Runner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, System.Action`1 setupStartInfo) (at
<...>

Reproduced with:
5.4.0f1, 5.4.4f1, 5.5.0p3, 5.6.0b2

Unable to reproduce with 5.3.7p3 and older 5.3 version due to other errors in scripts.