Alexey Rochev

Enabling CMAKE_INTERPROCEDURAL_OPTIMIZATION (LTO) causes executables to be linked twice

2

### Checklist - [X] I agree to follow the [Code of Conduct](https://github.com/flatpak/flatpak/blob/master/CODE_OF_CONDUCT.md) that this project adheres to. - [X] I have searched the [issue tracker](https://www.github.com/flatpak/flatpak-builder/issues) for a bug that matches...

EXTERNAL_INCLUDE env variable is not imported from VS dev environment

3

### Brief Issue Summary Running `C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\Tools\Launch-VsDevShell.ps1` script in PowerShell sets, among others, a `EXTERNAL_INCLUDE` environment variable with this (example) value: >C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.42.34433\include;C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.42.34433\ATLMFC\include;C:\Program...

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