Revert "su: allocate new pty (#1693)"

This reverts commit 935dc18faa.

userspace/ksud/src/mount.rs

@@ -1,5 +1,4 @@
 use anyhow::{anyhow, bail, Ok, Result};
-use std::fs::create_dir;
 
 #[cfg(any(target_os = "linux", target_os = "android"))]
 use anyhow::Context;
@@ -182,19 +181,6 @@ pub fn mount_tmpfs(dest: impl AsRef<Path>) -> Result<()> {
     Ok(())
 }
 
-#[cfg(any(target_os = "linux", target_os = "android"))]
-pub fn mount_devpts(dest: impl AsRef<Path>) -> Result<()> {
-    create_dir(dest.as_ref())?;
-    mount(
-        KSU_OVERLAY_SOURCE,
-        dest.as_ref(),
-        "devpts",
-        MountFlags::empty(),
-        "newinstance",
-    )?;
-    Ok(())
-}
-
 #[cfg(any(target_os = "linux", target_os = "android"))]
 pub fn bind_mount(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<()> {
     info!(
@@ -339,8 +325,3 @@ pub fn mount_overlay(
 pub fn mount_tmpfs(_dest: impl AsRef<Path>) -> Result<()> {
     unimplemented!()
 }
-
-#[cfg(not(any(target_os = "linux", target_os = "android")))]
-pub fn mount_devpts(_dest: impl AsRef<Path>) -> Result<()> {
-    unimplemented!()
-}