message: Add descriptions to the probestacks
diff: @@ -23,6 +23,7 @@ cfg_if::cfg_if! {
  extern "C" {
  pub fn __chkstk();
  }
  + /// The probestack for Windows when compiled with MSVC
  pub const PROBESTACK: unsafe extern "C" fn() = __chkstk;
  } else if #[cfg(all(target_os = "windows", target_env = "gnu"))] {
  extern "C" {
  @@ -31,6 +32,7 @@ cfg_if::cfg_if! {
  #[cfg(all(target_os = "windows", target_env = "gnu"))]
  pub fn ___chkstk();
  }
  + /// The probestack for Windows when compiled with GNU
  pub const PROBESTACK: unsafe extern "C" fn() = ___chkstk;
  } else if #[cfg(not(any(target_arch = "x86_64", target_arch = "x86")))] {
  // As per
  @@ -38,11 +40,13 @@ cfg_if::cfg_if! {
  // LLVM only has stack-probe support on x86-64 and x86. Thus, on any other CPU
  // architecture, we simply use an empty stack-probe function.
  extern "C" fn empty_probestack() {}
  + /// A default probestack for other architectures
  pub const PROBESTACK: unsafe extern "C" fn() = empty_probestack;
  } else {
  extern "C" {
  pub fn __rust_probestack();
  }
  + /// The probestack based on the Rust probestack
  pub static PROBESTACK: unsafe extern "C" fn() = __rust_probestack;
  }
  }
  