moxie.md (*movsi, [...]): Use xor to load the constant 0 when appropriate.

	* config/moxie/moxie.md (*movsi, *movhi, *movqi): Use xor to load
	the constant 0 when appropriate.
	* config/moxie/constraints.md: Add constraint O.

	* config/moxie/moxie.c (moxie_setup_incoming_varargs): Adjust
	to pass up to 6 32-bit argument values in registers.
	(moxie_function_arg): Ditto.
	(moxie_arg_partial_bytes): Ditto.
	* config/moxie/moxie.h (FUNCTION_ARG_ADVANCE): Ditto.
	(REG_PARM_STACK_SPACE): Ditto.
	(FUNCTION_ARG_REGNO_P): Ditto.

	* config/moxie/moxie.c (moxie_expand_prologue): Use dec
	instruction to allocate stack space.

From-SVN: r151579