Port to Fujitsu and a few bug fixes

Added

• Fujitsu compiler support

Fixed

• This fixes a small CMake bug which can lead to posix_predefined.x being built in the wrong build subdirectory when CMAKE_RUNTIME_OUTPUT_DIRECTORY is set*.
• Missing implementation of assertIsFinite_real80(). Apparently undetected until recent attempt to port to flang.
• Made support for REAL128 optional. (Port to nvfortran)

Changed

• Updated the CI to use Intel LLVM compilers
• Removed obsolete documentation