Divert LCC compiler as a new one, instead of treating it as GNU.
Since old times, Elbrus C/C++/Fortran Compiler (LCC) by MCST has been
passing checks for GNU compilers, so it has been identified as GNU.
Now, with intent of seriously upstreaming its support, it has been
added as a separate LCC compiler, and its version displays not a
supported GCC version, but LCC version itself (e.g. LCC 1.25.19 instead
of GNU 7.3.0).
This commit adds its support for detection, and also converts basically
every check like 'is this compiler GNU?' to 'is this compiler GNU or
LCC?'. The only places where this check is untouched, is where it
regards other platforms where LCC is unavailable (primarily non-Linux),
and where it REALLY differs from GNU compiler.
Note: this transition may break software that are already ported to
Elbrus, but hardly relies that LCC will be detected as GNU; still such
software is not known.
Small changes to the text and CMake code for the fourth step of the
tutorial:
* Remove parameter from endfunction call
* Standardize on "binary directory" for test location
* Add additional information about a Release build.
Issue: #22663
Add documentation for the configure_package_config_file() and
write_basic_package_version_file() commands.
Update the comment for the installation of those files to allow a
stopping point for the code display.
Issue: #22663
