Apparently, the 64bit Intel architecture is presented differently
on Linux and Windows.
Allow both variants for the command line, so that semantically the
command line argument can be seen as a lower case platform.machine.
Possible values are x86_64 and arm64.
Allows to use make_update.py in a cross-compile environment, like
building x86_64 macOS Blender from Apple Silicon machine.
Pull Request #104863