[RISCV] Apply clang_builtin_alias to overloaded builtins.

We only apply `clang_builtin_alias` to non-masked builtins.
Masked builtins could not use `clang_builtin_alias` because the
operand order is different between overloaded intrinsics and builtins.

A bunch of test cases need to be updated.

Differential Revision: https://reviews.llvm.org/D100658