gccrs: Fix ICE by adding check for enum candidate's in TypePath resolution

gccrs: Fix ICE by adding check for enum candidate's in TypePath resolution

Fixes #2479

gcc/rust/ChangeLog:

	* typecheck/rust-hir-trait-resolve.cc (TraitItemReference::resolve_item):
	always resolve the type even when its an a mandatory trait item
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::resolve_root_path):
	Add check for enum candidates otherwise you get undefined behaviour

gcc/testsuite/ChangeLog:

	* rust/compile/issue-2479.rs: New test.

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