Rework WindowServer to use select() in its main event loop.

The system can finally idle without burning CPU. :^)

There are some issues with scheduling making the mouse cursor sloppy
and unresponsive that need to be dealt with.

Kernel/init.cpp

@@ -37,6 +37,7 @@ VirtualConsole* tty3;
 Keyboard* keyboard;
 PS2MouseDevice* ps2mouse;
 GUIEventDevice* gui_event_device;
+VFS* vfs;
 
 #ifdef STRESS_TEST_SPAWNING
 static void spawn_stress() NORETURN;
@@ -62,8 +63,6 @@ static void init_stage2()
 {
     Syscall::initialize();
 
-    auto vfs = make<VFS>();
-
     auto dev_zero = make<ZeroDevice>();
     vfs->register_character_device(*dev_zero);
 
@@ -138,6 +137,9 @@ void init()
     gdt_init();
     idt_init();
 
+    VFS::initialize_globals();
+    vfs = new VFS;
+
     keyboard = new Keyboard;
     ps2mouse = new PS2MouseDevice;
     gui_event_device = new GUIEventDevice;
@@ -153,7 +155,6 @@ void init()
 
     MemoryManager::initialize();
 
-    VFS::initialize_globals();
     StringImpl::initialize_globals();
 
     PIT::initialize();