[llvm] [AArch64] Disable variadic tail-calls for ARM64EC (PR #78914)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

Is this supposed to be applied on top of #79067 ?

Briefly testing, it seems like the existing logic works correctly: if the argument list fits into four or less integer registers, we tail-call with a "stack size" of zero, and if there are more arguments, we refuse to tail-call.

https://github.com/llvm/llvm-project/pull/78914