Fix interaction between stack alignment and inline-asm stack clash protection

As reported in https://github.com/rust-lang/rust/issues/70143 alignment is not
taken into account when doing the probing. Fix that by adjusting the first probe
if the stack align is small, or by extending the dynamic probing if the
alignment is large.

Differential Revision: https://reviews.llvm.org/D84419

(cherry picked from commit f2c6bfa3)