Initial patches for IA-64 EFI (64-bit PE) support.

Initial patches for IA-64 EFI (64-bit PE) support.
	* pe.h (PEP64AOUTHDR): New header for PE+.
	(PEP64AOUTSZ): New macro.
	(IMAGE_SUBSYSTEM_UNKNOWN): New macro.
	(IMAGE_SUBSYSTEM_NATIVE): Ditto.
	(IMAGE_SUBSYSTEM_WINDOWS_GUI): Ditto.
	(IMAGE_SUBSYSTEM_WINDOWS_CUI): Ditto.
	(IMAGE_SUBSYSTEM_POSIX_CUI): Ditto.
	(IMAGE_SUBSYSTEM_WINDOWS_CE_GUI): Ditto.
	(IMAGE_SUBSYSTEM_EFI_APPLICATION): Ditto.
	(IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER): Ditto.
	(IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER): Ditto.
	* internal.h (PE_DEF_FILE_ALIGNMENT): Define only if not defined
	already.
	* ia64.h: New file.