* backend/rust-compile-expr.cc (CompileExpr::generate_closure_function):
Fix reference to node.
* backend/rust-mangle.cc (struct V0Path): Modified to accept closures.
(v0_crate_path): Modified to accept closures.
(v0_closure): New function to mangle closures.
(v0_path): Modified to accept closures
* util/rust-mapping-common.h (UNKNOWN_NODEID): Change to UINT32_MAX.
(UNKNOWN_HIRID): Change to UINT32_MAX.