invoke.texi (Option Summary): Document -mbranch-predict, -mreg-stack-fill-bug-workaro...

invoke.texi (Option Summary): Document -mbranch-predict, -mreg-stack-fill-bug-workaround and their negatives.

	* doc/invoke.texi (Option Summary) <MMIX Options>: Document
	-mbranch-predict, -mreg-stack-fill-bug-workaround and their
	negatives.
	(MMIX Options): Ditto.  Fix item/itemx typo for -mno-zero-extend.
	* config/mmix/mmix.c (mmix_target_asm_function_prologue): Rework
	kludge for pre-october-14th mmix versions to handle new-found bug
	with PUSHJ/PUSHGO and the register stack.
	* config/mmix/mmix.h (struct machine_function): Rename member
	has_call_value_without_parameters to has_call_without_parameters.
	All referers changed.
	(TARGET_MASK_REG_STACK_FILL_BUG, TARGET_DEFAULT
	TARGET_MASK_BRANCH_PREDICT): New macros.
	(TARGET_SWITCHES): New options -mreg-stack-fill-bug-workaround,
	-mno-reg-stack-fill-bug-workaround.
	* config/mmix/mmix.md ("call"): Set struct machine member
	has_call_without_parameters.

From-SVN: r48558