gccrs: Only the last segment should resolve to an expr item

This doesnt fix that linked issue but its part of the fix thats needed.

Addresses Rust-GCC/gccrs#4865

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-path.cc (TypeCheckExpr::resolve_segments):
	use probe expr on last seg

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