[2024-09-30: no longer in use as fedora-clang and debian-clang reqular checks
 have switched to LLVM 19. It also records pa]kages failing with libc++ but
not with debian-clang which uses GCC's libsrdc++ .]

Tests as for the main fedora-clang checks but using LLVM 19
including its flang-new as the Fortran compiler.
Other details as for 
https://www.stats.ox.ac.uk/pub/bdr/Rconfig/r-devel-linux-x86_64-fedora-clang .

Releave notes were available at

https://releases.llvm.org/

including

https://releases.llvm.org/19.1.0/tools/clang/docs/ReleaseNotes.html
https://releases.llvm.org/19.1.0/projects/libcxx/docs/ReleaseNotes.html

Current results are from LLVM-19.1.2.  Some binary distributions
are available at https://github.com/llvm/llvm-project/releases
and in Debian unstable.