Work around missing lib on linux (Issue #4972) (#4975)

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

@@ -13,6 +13,18 @@ mod test {
     extern crate std;
     use super::*;
 
+    #[test]
+    fn pull_in_externs() {
+        // Rust on Linux excludes the solana_sdk_bpf_test library unless there is a
+        // direct dependency, use this test to force the pull in of the library.
+        // This is not necessary on macos and unfortunate on Linux
+        // Issue #4972
+        extern crate solana_sdk_bpf_test;
+        use solana_sdk_bpf_test::*;
+        unsafe { sol_log_("X".as_ptr(), 1) };
+        sol_log_64_(1, 2, 3, 4, 5);
+    }
+
     #[test]
     fn test_work() {
         assert_eq!(3, work(1, 2));