Vendor __rust_probestack for Rust 1.89+

Starting with Rust 1.89, the __rust_probestack symbol from
compiler-builtins is name-mangled and no longer exported, causing
linker failures when building wasmer-vm on x86/x86_64.

Conditionally vendor the probestack assembly from compiler-builtins
when building with Rust >= 1.89, using rustversion for detection.
On older Rust versions the behavior is unchanged.

Cherry-picked from upstream wasmerio/wasmer@fc021be5c6f with a
fix to use the old cargo: build script syntax for MSRV compatibility.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: deuszx