Reworking the memory system to not commit 3gb and to properly alloc data.

Now only 512MB is committed on startup. Loaded XEXs are placed into their
required addresses in the 0x8... range. Kernel structures are allocated
from the normal heap like other data. There should no longer be any magical
pointers.

src/xenia/kernel/modules/xboxkrnl/xboxkrnl_video.cc

@@ -159,6 +159,12 @@ SHIM_CALL VdSetGraphicsInterruptCallback_shim(
 // no op?
 
 
+// VdCallGraphicsNotificationRoutines
+// r3 = 1
+// r4 = ?
+// callbacks get 0, r3, r4
+
+
 }  // namespace xboxkrnl
 }  // namespace kernel
 }  // namespace xe