gui+system: Add pledges to loginui and startui

Big oof moment.

Thankfully kernel panics sometimes just give you the exact source of the problem :P
"-- KERNEL PANIC: Check failed at kernel/src/sys/waitpid.cpp:67, in sys_waitpid: !target->dead() --"

gui/loginui.cpp

@@ -14,6 +14,7 @@
 #include <os/FileSystem.h>
 #include <os/IPC.h>
 #include <os/Process.h>
+#include <os/Security.h>
 #include <pwd.h>
 #include <shadow.h>
 #include <sys/stat.h>
@@ -45,6 +46,8 @@ Result<int> luna_main(int argc, char** argv)
         return 1;
     }
 
+    TRY(os::Security::pledge("stdio rpath wpath proc exec id", nullptr));
+
     setsid();
 
     bool success = os::IPC::Notifier::run_and_wait(

gui/wind/main.cpp

@@ -58,7 +58,7 @@ Result<int> luna_main(int argc, char** argv)
 {
     srand((unsigned)time(NULL));
 
-    TRY(os::Security::pledge("stdio rpath wpath cpath unix proc exec tty id", NULL));
+    TRY(os::Security::pledge("stdio rpath wpath cpath unix tty id", NULL));
 
     StringView socket_path = "/tmp/wind.sock";
     StringView system_socket_path = "/tmp/wsys.sock";
@@ -128,7 +128,7 @@ Result<int> luna_main(int argc, char** argv)
     TRY(fds.try_append({ .fd = server->fd(), .events = POLLIN, .revents = 0 }));
     TRY(fds.try_append({ .fd = system_server->fd(), .events = POLLIN, .revents = 0 }));
 
-    TRY(os::Security::pledge("stdio rpath wpath cpath unix proc exec", NULL));
+    TRY(os::Security::pledge("stdio rpath wpath cpath unix", NULL));
 
     while (1)
     {

kernel/src/sys/waitpid.cpp

@@ -64,7 +64,7 @@ Result<u64> sys_waitpid(Registers* regs, SyscallArgs args)
             check(current->child_being_waited_for != -1);
 
             target = TRY(Result<Process*>::from_option(Scheduler::find_by_pid(current->child_being_waited_for), ESRCH));
-            check(!target->dead());
+            check(target->dead());
         }
         else
             target = child.value();

system/startui.cpp

@@ -15,6 +15,7 @@
 #include <os/IPC.h>
 #include <os/Main.h>
 #include <os/Process.h>
+#include <os/Security.h>
 #include <pwd.h>
 #include <stdlib.h>
 #include <sys/stat.h>
@@ -67,6 +68,8 @@ Result<int> luna_main(int argc, char** argv)
     parser.add_value_argument(username, 'u', "user", "the user to start the UI session as");
     parser.parse(argc, argv);
 
+    TRY(os::Security::pledge("stdio rpath wpath cpath proc exec id", nullptr));
+
     if (geteuid() != 0)
     {
         os::eprintln("error: %s can only be started as root.", argv[0]);