[llvm] [InlineAsm] Steal a bit to denote a register is spillable (PR #70738)

[Nick Desaulniers via llvm-commits]

nickdesaulniers wrote:

>> For the sake of brevity, can we go with just foldable? Or memFoldable?

> Fine with me too.

Done in https://github.com/llvm/llvm-project/pull/70738/commits/14d69cf1ee4abca98a175ff5ab0cd4be2ee21151 PTAL

https://github.com/llvm/llvm-project/pull/70738