This PR fixes libexpat compilation on a specific situation (having cl.exe/Visual Studio output not being in english), already reported and discussed on the libexpat repository https://github.com/libexpat/libexpat/issues/418.
My solution to this is to apply the same virtual env solution used in libs/ghostscript, by forcing the cl.exe to output in English, altrogh this (while I have not tested it myself) should require the english language pack to be installed on the system.
The cmake regex are not aware of multilanguages in compilers in the last version of cmake (3.23.1 at this time), I am not aware of any way to dynamically set an environment variable without updating the system on cmake, which is why I have decided to fall back to this solution.
This issue can be reproduced if any default language is set other than English in Visual Studio.