Util::CompilerShader should handle malformed defines

[alandtse]

https://github.com/doodlum/skyrim-community-shaders/blob/ef9acef6b795c7761168cfdb4c96d9f9738ef696/src/Util.cpp#L119-L120

Will fail if the defines is not a valid pair. This will result in the defines not being generated at all.

See necessary changes here that discovered issue: 514f217 (#299)

Util::CompileShader(L"Data\\Shaders\\TerrainOcclusion\\AOGen.cs.hlsl", { {} }, "cs_5_0")

which was fixed with:

Util::CompileShader(L"Data\\Shaders\\TerrainOcclusion\\AOGen.cs.hlsl", {}, "cs_5_0")

The { {} } is a bad define since it's not a pair, `{ {,} }