"Warning! PATH too long installer unable to modify PATH!" using CMake Windows installer and PATH length > 1024
## Steps to reproduce
1. Add stuff to the PATH variable to make it longer than 1024 characters.
2. Install e.g. https://www2.graphviz.org/Packages/stable/windows/10/cmake/Release/x64/graphviz-install-2.44.1-win64.exe and let the installer set your PATH.
## Expected Behaviour
No problem
## Actual Behaviour
A dialog with the text "Warning! PATH too long installer unable to modify PATH!" shows up.
## OS Version
Windows 10
## Graphviz Version
2.44.1
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