- point to main Calamares site in the 'part of' headers instead
of to github (this is the "this file is part of Calamares"
opening line for most files).
- remove boilerplate from all source files, CMake modules and completions,
this is the 3-paragraph summary of the GPL-3.0-or-later, which has
a meaning entirely covered by the SPDX tag.
- there **is** another source of information about the CPU,
so in the test use that to cross-check what hostCPU() says.
NB: it's probably a good idea to fall back on the same file
in hostCPU() for better accuracy.
