[Patch AArch64 4/4] Add -moverride tuning command, and wire it up for

[Patch AArch64 4/4] Add -moverride tuning command, and wire it up for
 control of fusion and fma-steering

gcc/

	* config/aarch64/aarch64.opt: (override): New.
	* doc/invoke.texi (override): Document.
	* config/aarch64/aarch64.c (aarch64_flag_desc): New
	(aarch64_fusible_pairs): Likewise.
	(aarch64_tuning_flags): Likewise.
	(aarch64_tuning_override_function): Likewise.
	(aarch64_tuning_override_functions): Likewise.
	(aarch64_parse_one_option_token): Likewise.
	(aarch64_parse_boolean_options): Likewise.
	(aarch64_parse_fuse_string): Likewise.
	(aarch64_parse_tune_string): Likewise.
	(aarch64_parse_one_override_token): Likewise.
	(aarch64_parse_override_string): Likewise.
	(aarch64_override_options): Parse the -override string if it
	is present.

From-SVN: r225018