CrossCompileTool module fails to build due to missing include

The include for VulkanConfiguration.h was added to VulkanBackend.h, which is one of the external dependencies for the CrossCompileTool. This include is not complete however. This results in this module failing to compile.

Either the full include needs to be given, as in \Runtime\VulkanRHI\Public\VulkanConfiguration.h or the following line needs to be added to the CrossCompileTool.build.cs file

 PublicIncludePaths.Add("Runtime/VulkanRHI/Public"); 

Regression?: Yes
This include statement was not present in 4.13.1 (//UE4/Release-4.13/ CL# 3142249)
This include statement was added prior to 4.14 Preview 1 (//UE4/Release-4.14/ CL# 3167010)

1. Open the UE4.sln for a source build on 4.14 (CL# 3167010) or later
2. Right-click the CrossCompileTool module and select Build
   Result: The build fails due to the compiler not being able to find the included file "VulkanConfiguration.h"
   Expected: The build should succeed