Add support for post shutdown function (#251)

Author: joehoyle

src/builders/module.rs

@@ -126,6 +126,19 @@ impl ModuleBuilder {
         self
     }
 
+    /// Sets the post request shutdown function for the extension.
+    ///
+    /// This function can be useful if you need to do any final cleanup at the
+    /// very end of a request, after all other resources have been released. For
+    /// example, if your extension creates any persistent resources that last
+    /// beyond a single request, you could use this function to clean those up. # Arguments
+    ///
+    /// * `func` - The function to be called when shutdown is requested.
+    pub fn post_deactivate_function(mut self, func: extern "C" fn() -> i32) -> Self {
+        self.module.post_deactivate_func = Some(func);
+        self
+    }
+
     /// Sets the extension information function for the extension.
     ///
     /// # Arguments