nr2.0: Resolve paths which start with Self

nr2.0: Resolve paths which start with Self

gcc/rust/ChangeLog:

	* resolve/rust-forever-stack.hxx
	(ForeverStack::find_starting_point): Be more careful about
	applying ForeverStack::find_closest_module.
	(ForeverStack::resolve_segments): Allow traversal into parent
	nodes when not in a module node or root node, which
	ForeverStack::find_starting_point previously made moot through
	use of ForeverStack::find_closest_module. Also, when a child
	node lookup fails when resolving in the type namespace, attempt
	a rib lookup as a fallback.
	* resolve/rust-late-name-resolver-2.0.cc
	(Late::visit): Avoid throwing a resolution error for type paths
	when the typechecker may be able to finish the resolution. Also,
	throw an error when a resolution is ambiguous.

gcc/testsuite/ChangeLog:

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

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