Attempting to build the BuildPatchTool program fails due to a missing .h that was likely relocated. This may be related to, and is at least similar to, another issue where ShaderCacheTool is also unable to be built:
This did not occur in 4.17.2
This does occur in 4.18
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-51925 in the post.