Mega KD64 revival patch:

Mega KD64 revival patch:
KD64
- Fix some 64-bit issues and some x86 specificness.
- Sub out some KdpTrap cases more properly.
- Implement support for .crash and .reboot. Does not seem to work currently because of weird issues.
- Implement KdpDprintf to send strings directly to the debugger from inside of KD64. Use it in KdEnterDebugger instead of DbgPrint so we won't try to enter the debugger recursively.
- Implement KdUpdateDataBlock to set the KeUserCallbackDispatcher pointer in the debugger block after its address is retrieved from ntdll.
- Don't assume breakpoints are 1 byte long in portable code -- use KD_BREAKPOINT_SIZE and define it per architecture.
- KdpStub: KdEnableDebugger returns NTSTATUS, not TRUE/FALSE.

Other
- wdbgexts.h: Properly define CURRENT_KD_SECONDARY_VERSION for AMD64.
- Make PsNtosImageBase pointer-sized as it should be.
- Change the definition of KDSTATUS so it is guaranteed to be 32-bit.
- Fix a critical bug in KiRestoreProcessorControlState: it didn't clear the busy flag in the TSS before reloading the task register, resulting in a GPF if we tried to reload the same register.
- Add macros for getting and setting special purpose registers (the Program Counter and the "return register") in portable code instead of using #ifdef every time. Do likewise for setting IMAGE_FILE_MACHINE_XXX, using a new IMAGE_FILE_MACHINE_ARCHITECTURE macro.
- Don't refer to the Program Counter as "Eip" in portable code.
- Define DBG_STATUS_CONTROL_C for assembly code and use it in KeUpdateSystemTime.

svn path=/trunk/; revision=43283