[vcpkg] Fix external include path

[RT2Code]

My external include path change #18820 was broken by an unfortunate merge. The definition of the external include path relies on the _ZVcpkgCurrentInstalledDir property and therefore must be defined after it.

[Neumann-A]

Still wondering if the integration in vs2015 is ok with this?

[jasjuang]

After I apply the diff of this PR, is it supposed to just work? The vcpkg include directories, e.g. vcpkg\installed\x64-windows\include still shows up in "Additional Include Directories" instead of "External Include Directories" for me. The bare minimal example to reproduce this is

CMakeLists.txt

set(CMAKE_TOOLCHAIN_FILE $ENV{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake)

cmake_minimum_required(VERSION 3.20)

project(example)

find_package(CGAL REQUIRED)

add_executable(${PROJECT_NAME} main.cpp)

target_link_libraries(${PROJECT_NAME} PUBLIC CGAL::CGAL)

main.cpp

int main() { return 0; }

mkdir build && cd build
cmake -A x64 ..

Double click example.sln and right click to look at the properties.

I also ran bootstrap-vcpkg.bat but nothing changes, I do notice it is downloading tools from 11/15. Is this the reason why it's not working? Or am I totally misunderstanding the purpose of this PR? It will be phenomenal if vcpkg installed third-party libraries can be treated as /external. A -isystem equivalent for Windows is really sorely needed.

[Neumann-A]

@jasjuang msbuild and cmake integration are two different things. This pr is about the msbuild integration. What you see is probably solved with cmake 3.22. It is a cmake issue.

[jasjuang]

@Neumann-A thanks for the clarification, but I think it's not solved in cmake yet https://gitlab.kitware.com/cmake/cmake/-/issues/17904

[BillyONeal]

Thanks for the fix and confirmation!