LLVM Clang RISC-V Now Supports LTO

With the recent release of LLVM 9.0 the RISC-V back-end was promoted from an experimental CPU back-end to being made "official" for this royalty-free CPU ISA. Work though isn't over on the LLVM RISC-V support with new features continuing to land, like link-time optimizations (LTO) most recently being enabled within the Clang 10 code...