rs6000: Parsing of overload input file

rs6000: Parsing of overload input file

2021-06-07  Bill Schmidt  <wschmidt@linux.ibm.com>

gcc/
	* config/rs6000/rs6000-gen-builtins.c (ovld_stanza): New struct.
	(MAXOVLDSTANZAS): New macro.
	(ovld_stanzas): New variable.
	(curr_ovld_stanza): Likewise.
	(MAXOVLDS): New macro.
	(ovlddata): New struct.
	(ovlds): New variable.
	(curr_ovld): Likewise.
	(max_ovld_args): Likewise.
	(parse_ovld_entry): New function.
	(parse_ovld_stanza): Likewise.
	(parse_ovld): Implement.