Replace FIXME with an issue link

Author: Aaron1011

sdk/src/entrypoint_native.rs

@@ -58,8 +58,10 @@ macro_rules! declare_name {
                 // `declare_name(foo)`
                 //
                 // See the `respan!` macro for more details.
-                // FIXME: Use `crate::respan!` once https://github.com/rust-lang/rust/pull/72121
-                // is merged.
+                // This should use `crate::respan!` once https://github.com/rust-lang/rust/pull/72121
+                // is merged: see https://github.com/solana-labs/solana/issues/10933.
+                // For now, we need to use `::solana_sdk`
+                //
                 // `respan!` respans the path `$crate::id`, which we then call (hence the extra
                 // parens)
                 (