use executable flag for legacy bpf loader

sdk/src/account.rs

@@ -766,6 +766,14 @@ pub const PROGRAM_OWNERS: &[Pubkey] = &[
 
 /// Return true if the account program is executable.
 pub fn is_executable(account: &AccountSharedData) -> bool {
+    // bpf_loader still relies on `executable` on the program account. When the
+    // program account is finalized, the loader will mark `executable` flag on
+    // the account. Once we disable the deployment of these two loaders, we can
+    // remove the following dependency on `executable`.
+    if bpf_loader::check_id(account.owner()) || bpf_loader_deprecated::check_id(account.owner()) {
+        account.executable();
+    }
+
     if account.data().is_empty() {
         // empty account is not executable.
         return false;