- This is based off BuildPhysx.Automation.cs and could be unified with this in the future.
- Update some CMakeLists.txt to support this.
- Convert ICU CMakeLists.txt to support cmake 3.5.2 that ships with the engine.
- Fix up some whitespace in BuildPhysX.
#review-11538204 @brian.white
#jira UE-81798
#rb david.harvey
[CL 11597283 by Anthony Bills in 4.25 branch]