Flag /external:I not handled right

[d-musique]

Hi, when the command line contains a directive in the form -external:I/path/to/include, the headers are not found.
fatal error C1083: Cannot open include file: 'SDL3/SDL.h'

This is msvc-wine 32b504c with compiler 19.50.35719.

Cmake uses this flag when the compiler is 19.29.30036.3 or later.
As a workaround, the feature can be turned off by commenting the lines below.
https://github.com/Kitware/CMake/blob/c7c1142c89a0a4e4cc4ba253cfc62a69f8ea2af8/Modules/Compiler/MSVC.cmake#L20-L24

See also: https://learn.microsoft.com/en-us/cpp/build/reference/external-external-headers-diagnostics?view=msvc-170