[clang] [Clang][AArch64] Use __clang_arm_builtin_alias for overloaded svreinterpret's (PR #92427)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

> Thinking about it a bit more, maybe we can just do some magic to make things work? Say, if you specify `__attribute__((target("sve"))) __arm_streaming_compatible`, and the caller is in streaming mode, allow the call even if the caller doesn't have SVE proper.

Thinking a bit more, this is probably not quite what we want: even if the function body itself is streaming compatible, it might call non-streaming functions that require SVE.  Maybe spell this something like `__attribute__((target("sve-or-streaming"))) __arm_streaming_compatible`.

https://github.com/llvm/llvm-project/pull/92427