PR82687, g++.dg/asan/default-options-1.C fails with PR82575 fix

PR82687, g++.dg/asan/default-options-1.C fails with PR82575 fix

The problem with making discarded symbols hidden is that the
non-default visibility is sticky.  When symbols other than the
__gnu_lto ones are discarded that turns out to be a bad idea.

	PR lto/82687
	PR lto/82575
	* simple-object-elf.c (simple_object_elf_copy_lto_debug_sections):
	Only make __gnu_lto symbols hidden.  Delete outdated comment.
	Silence ISO C warning.

From-SVN: r254042