* aarch64/crt0.S (GEN_DWORD): New macro definition.
	(PTR_REG): Ditto.
	(PTR_SIZE): Ditto.
	(PTR_LOG_SIZE): Ditto.
	(start): Use GEN_DWORD to replace the .dword of HeapBase,
	__bss_start__, __bss_end__, FUNCTION(_fini), env and
	CommandLine; when __ILP32__ is defined, set the stack base to
	the top end of the 32-bit address space if the returned value
	from the Angel API call is larger than or equal to 4 GiB.
	Also carry out sanity check on the heap base; abort if the
	base is larger than or equal to 4 GiB.  Use other new
	macros in the instructions that processes the argv arrays.
	(StackBase): New lable; replace __stack_base__.
	(__stack_base__): Set with StackBase or StackBase + 4.