Split out Rust BPF no-std stuff (#4968)

programs/bpf/rust/128bit_dep/Cargo.toml

@@ -15,5 +15,4 @@ edition = "2018"
 solana-sdk-bpf-utils = { path = "../../../../sdk/bpf/rust/rust-utils", version = "0.17.0" }
 
 [workspace]
-members = []
-
+members = []

programs/bpf/rust/128bit_dep/src/lib.rs

@@ -7,3 +7,14 @@ extern crate solana_sdk_bpf_utils;
 pub fn work(x: u128, y: u128) -> u128 {
     x + y
 }
+
+#[cfg(test)]
+mod test {
+    extern crate std;
+    use super::*;
+
+    #[test]
+    fn test_work() {
+        assert_eq!(3, work(1, 2));
+    }
+}