kernel: throne_tracker: offload to kthread (tiann[#2632](https://github.com/SukiSU-Ultra/SukiSU-Ultra/issues/2632))

Run throne_tracker() in kthread instead of blocking the caller.
Prevents full lockup during installation and removing the manager.

First run remains synchronous for compatibility purposes (FDE, FBEv1, FBEv2)

Features:
- run track_throne() in a kthread after the first synchronous run
- prevent duplicate thread creation with a single-instance check
- spinlock-on-d_lock based polling adressing possible race conditions.

Race conditions adressed
- single instance kthread lock, smp_mb()
- is_manager_apk, apk, spinlock-on-d_lock based polling

This is a squash of:
https://github.com/tiann/KernelSU/pull/2632

Rebased on top of
https://github.com/tiann/KernelSU/pull/2757

Original skeleton based on:
`kernelsu: move throne_tracker() to kthread`
`kernelsu: check locking before accessing files and dirs during searching manager`
`kernelsu: look for manager UID in /data/system/packages.list, not /data/system/packages.list.tmp`
0b05e927...8783badd

Co-Authored-By: backslashxx <118538522+backslashxx@users.noreply.github.com>
Co-Authored-By: Yaroslav Zviezda <10716792+acroreiser@users.noreply.github.com>
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>

kernel/sucompat.c

@@ -28,8 +28,6 @@
 #define SU_PATH "/system/bin/su"
 #define SH_PATH "/system/bin/sh"
 
-extern void escape_to_root(void);
-
 static const char sh_path[] = "/system/bin/sh";
 static const char ksud_path[] = KSUD_PATH;
 static const char su[] = SU_PATH;
@@ -188,7 +186,7 @@ int ksu_handle_execveat_sucompat(int *fd, struct filename **filename_ptr,
 	pr_info("do_execveat_common su found\n");
 	memcpy((void *)filename->name, ksud_path, sizeof(ksud_path));
 
-	escape_to_root();
+	escape_to_root(true);
 
 	return 0;
 }
@@ -237,7 +235,7 @@ int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user,
 	pr_info("sys_execve su found\n");
 	*filename_user = ksud_user_path();
 
-	escape_to_root();
+	escape_to_root(true);
 
 	return 0;
 }