[llvm] [TableGen] Rework `EmitIntrinsicToBuiltinMap` (PR #104681)

[Artem Belevich via llvm-commits]

Artem-B wrote:

> ```c++
> static constexpr char BuiltinNames[] = {
>   'd', 'm', 'b', '\000', 'd', 's', 'b', '\000', 'i', 's', 'b', '\000', 'M', 'o', 'v',
>   'e', 'F', 'r', 'o', 'm', 'C', 'o', 'p', 'r', 'o', 'c', 'e', 's', 's', 'o',
>   'r', '\000', 'M', 'o', 'v', 'e', 'F', 'r', 'o', 'm', 'C', 'o', 'p', 'r', 'o',
>   'c', 'e', 's', 's', 'o', 'r', '2', '\000', '_', 'd', 'm', 'b', '\000', '_', 'd',
>   's', 'b', '\000', '_', 'i', 's', 'b', '\000',
>   };
> ```

Just curious. Would it make sense to generate string literals instead. Makes it more useful for grepping for the string values.
> ```c++
> static constexpr char BuiltinNames[] = 
>   "dmb\000" 
>   "dsb\000"
>   "isb\000"
>   "MoveFromCoprocessor\000"
>   "MoveFromCoprocessor2\000"
>   "_dmb\000"
>   "_dsb\000"
>   "_isb\000"
>   };
> ```


https://github.com/llvm/llvm-project/pull/104681