i386: move alignment defaults to processor_costs.

i386: move alignment defaults to processor_costs.

2018-09-17  Martin Liska  <mliska@suse.cz>

	* common/config/i386/i386-common.c (ix86_get_valid_option_values):
	Use processor_names table.
	* config/i386/i386.c (ix86_default_align): Use
	processor_cost_table for alignment values.
	(ix86_option_override_internal): Use processor_names.
	(ix86_function_specific_print): Likewise.
	* config/i386/i386.h (struct processor_costs):
	Add alignment values.
	(struct ptt): Remove and replace with const char *.
	* config/i386/x86-tune-costs.h (struct processor_costs):
	Declare default alignments for all costs.

From-SVN: r264359