Kernel: Fix broken destruction order for Process/Thread.

Kernel/.gitignore

@@ -7,3 +7,4 @@ kernel.map
 _fs_contents
 sync-local.sh
 *.pcap
+eth_null*

Kernel/Process.cpp

@@ -617,7 +617,7 @@ Process::Process(String&& name, uid_t uid, gid_t gid, pid_t ppid, RingLevel ring
 
 Process::~Process()
 {
-    dbgprintf("~Process{%p} name=%s pid=%d\n", this, m_name.characters(), pid());
+    dbgprintf("~Process{%p} name=%s pid=%d, m_fds=%d\n", this, m_name.characters(), pid(), m_fds.size());
     InterruptDisabler disabler;
     system.nprocess--;
 
@@ -1930,6 +1930,8 @@ void Process::finalize()
             }
         }
     }
+
+    m_dead = true;
 }
 
 void Process::die()

Kernel/Process.h

@@ -53,8 +53,7 @@ public:
         Ring3 = 3,
     };
 
-    // FIXME(Thread): Is this really how this should work?
+    bool is_dead() const { return m_dead; }
-    bool is_dead() const { return main_thread().state() == Thread::State::Dead; }
 
     Thread::State state() const { return main_thread().state(); }
 
@@ -311,6 +310,7 @@ private:
     HashTable<gid_t> m_gids;
 
     bool m_being_inspected { false };
+    bool m_dead { false };
 
     int m_next_tid { 0 };
 };

Kernel/Scheduler.cpp

@@ -72,7 +72,7 @@ bool Scheduler::pick_next()
 
         if (thread.state() == Thread::BlockedWait) {
             process.for_each_child([&] (Process& child) {
-                if (child.state() != Thread::Dead)
+                if (!child.is_dead())
                     return true;
                 if (thread.waitee_pid() == -1 || thread.waitee_pid() == child.pid()) {
                     thread.m_waitee_pid = child.pid();