[Clang][CodeGen] `typeid` needs special care when `type_info` is not in the default AS

After https://reviews.llvm.org/D153092, for targets that use a non-default AS for globals, an "interesting" situation arises around typeid and its paired type, type_info:

- on the AST level, the type_info interface is defined with default / generic addresses, be it for function arguments, or for this;
- in IR, type_info values are globals, and thus pointers to type_info values are pointers to global

This leads to a mismatch between the function signature / formal type of the argument, and its actual type. Currently we try to handle such mismatches via `bitcast`, but that is wrong in this case, since an `ascast` is required. This patch ensures that iff the pointer to `type_info` points to a non-default AS, an ascast is inserted so as to match the `typeid` interface / return value type.

Reviewed by: yaxunl

Differential Revision: https://reviews.llvm.org/D157452