Resolve used_underscore_items pedantic clippy lint in test

    warning: used underscore-prefixed item
       --> tests/test_item.rs:240:21
        |
    240 |                     [<_jit_ $fn>]($arg);
        |                     ^^^^^^^^^^^^^^^^^^^
    ...
    246 |     jit_reexport!(address, node: ());
        |     -------------------------------- in this macro invocation
        |
    note: item is defined here
       --> tests/test_item.rs:234:5
        |
    234 |     fn _jit_address(_node: ()) {}
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#used_underscore_items
        = note: `-W clippy::used-underscore-items` implied by `-W clippy::pedantic`
        = help: to override `-W clippy::pedantic` add `#[allow(clippy::used_underscore_items)]`
        = note: this warning originates in the macro `jit_reexport` (in Nightly builds, run with -Z macro-backtrace for more info)

tests/test_item.rs

@@ -231,13 +231,13 @@ mod test_type_in_fn_arg {
 
     use paste::paste;
 
-    fn _jit_address(_node: ()) {}
+    fn jit_address(_node: ()) {}
 
     macro_rules! jit_reexport {
         ($fn:ident, $arg:ident : $typ:ty) => {
             paste! {
                 pub fn $fn($arg: $typ) {
-                    [<_jit_ $fn>]($arg);
+                    [<jit_ $fn>]($arg);
                 }
             }
         };