LLVM Compiler Optimizations for RVV

This is a version of the LLVM compiler that fulfills the EPI requirements when it comes to vectorization for RISC-V Vector Extension. This compiler includes an implementation of the EPI-specific intrinsics and the vectorizer for the RISC-V Vector Extension. This compiler enables vectorization of applications using the RISC-V Vector Extension either using the mentioned intrinsics or the automatic vectorization mechanism. The vectorization mechanism can be triggered automatically or explicitly requested via pragma annotations such as #pragma clang loop or #pragma omp simd.