Add option to enable global namespace (#497)

Disabled by default.
To enable/disable use terminal with root.

To enable:
echo 1 > /sys/module/ksu/parameters/global_namespace_enable

To disable:
echo 0 > /sys/module/ksu/parameters/global_namespace_enable

Value will be reset to 0 (disabled) on reboot.

kernel/ksu.c

@@ -1,5 +1,6 @@
 #include "linux/fs.h"
 #include "linux/module.h"
+#include "linux/moduleparam.h"
 #include "linux/workqueue.h"
 
 #include "allowlist.h"
@@ -9,6 +10,9 @@
 #include "ksu.h"
 #include "uid_observer.h"
 
+int global_namespace_enable;
+module_param(global_namespace_enable, int, S_IRUSR | S_IWUSR);
+
 static struct workqueue_struct *ksu_workqueue;
 
 bool ksu_queue_work(struct work_struct *work)