rust: fix ICE when compiling impl block for !

rust: fix ICE when compiling impl block for !

We need to resolve the never type which is its own special AST node so it
doesnt magically get handled like the regular builtin type paths such as
i32.

Fixes #3035

gcc/rust/ChangeLog:

	* resolve/rust-ast-resolve-type.cc (ResolveType::visit):
	handle never type
	(ResolveTypeToCanonicalPath::visit): likewise
	* resolve/rust-ast-resolve-type.h: missing never type
	* resolve/rust-name-resolver.cc (Resolver::generate_builtins):
	track never type node_id
	(Resolver::setup_builtin): likewise
	* resolve/rust-name-resolver.h: new never type getter

gcc/testsuite/ChangeLog:

	* rust/compile/nr2/exclude: nr2 cant handle this
	* rust/compile/issue-3035.rs: New test.

Signed-off-by: Philip Herron <herron.philip@googlemail.com>