CMake cleaning

MR imported from FW4SPL/fw4spl!318

What does this MR do?

This MR cleans sight CMake scripts:

• removed unused platform
• removed racy backward compatibility

How to test it?

> cmake . && make

Data

• no data required

Additional tests to run

• Build on Windows
• Build on Linux
• Build on macOS
• Build on Android

Related MR

• fw4spl-ogre!142
• fw4spl-ar!161