Add hulk.gdt module and create our own GDT

src/hulk/hulk.d

@@ -13,6 +13,7 @@ import hulk.klog;
 import hulk.hurl;
 import hulk.hippo;
 import hulk.pci;
+import hulk.gdt;
 
 extern extern(C) __gshared ubyte _hulk_total_size;
 
@@ -31,6 +32,7 @@ private __gshared HulkHeader hulk_header = {
  */
 void hulk_start()
 {
+    gdt.initialize();
     fb.initialize(cast(uint *)HULK_VIRTUAL_FRAMEBUFFER_ADDRESS, hulk_header.bootinfo.fb.width, hulk_header.bootinfo.fb.height, hulk_header.bootinfo.fb.stride);
     console.initialize();
     console.clear();