LTO: pick up -fcf-protection flag for the link step

LTO: pick up -fcf-protection flag for the link step

2020-07-14  Matthias Klose  <doko@ubuntu.com>

	PR lto/95604
	* lto-wrapper.c (merge_and_complain): Add decoded options as parameter,
	error on different values for -fcf-protection.
	(append_compiler_options): Pass -fcf-protection option.
	(find_and_merge_options): Add decoded options as parameter,
	pass decoded_options to merge_and_complain.
	(run_gcc): Pass decoded options to find_and_merge_options.
	* lto-opts.c (lto_write_options): Pass -fcf-protection option.