There are overloaded version for vector intrinsics. Currently, we use
function wrapper and `__overloadable__` attributes for them. It increases
the build/test time a lot.
In this patch, we define __clang_riscv_builtin_alias for RISC-V
intrinsics and use this attribute to map the overloaded version to the
In our downstream testing, it could decrease the testing time from 6.3
seconds to 3.7 seconds for vloxei.c test.