nr2.0: Handle lang item type path segments

nr2.0: Handle lang item type path segments

gcc/rust/ChangeLog:

	* resolve/rust-forever-stack.hxx
	(ForeverStack::find_starting_point): Stop when hitting a lang
	item segment.
	(ForeverStack::resolve_segments): Resolve lang item segments.
	(ForeverStacl::resolve_path): Handle single segment lang item
	paths and add comment.
	* util/rust-unwrap-segment.cc
	(unwrap_segment_get_lang_item): Add.
	* util/rust-unwrap-segment.h
	(unwrap_segment_get_lang_item): Add.

gcc/testsuite/ChangeLog:

	* rust/compile/nr2/exclude: Remove entries.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>