Run the `clang-format.bash` script to update all our C and C++ code to a
new style defined by `.clang-format`.  Use `clang-format` version 15.

* If you reached this commit for a line in `git blame`, re-run the blame
  operation starting at the parent of this commit to see older history
  for the content.

* See the parent commit for instructions to rebase a change across this
  style transition commit.

Fixes: #24315

Specify the clang-format version in the attribute value instead of its
name.

Issue: #24315

Previously we added the language standard flag near the end of all
options, even after those added by `add_compile_options` and friends.
However, on some compilers such as MSVC, the `-std` flag may reset
defaults for flags that precede it on the command line.  Move the
language standard flag to before all other flags that CMake adds for
other abstractions, and before those added by `add_compile_options`.

`CMAKE_<LANG>_FLAGS` should still precede the language flags though,
because they are meant to be treated as language-wide modifications to
the compiler defaults, similar to `$CC $CFLAGS`.

Fixes: #23860
Fixes: #24170

Fixes: #22929

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.

Fix the warning: `potential leak of memory pointed to by "vp"`.