exec_list: Add pop_head

src/glsl/list.h

@@ -377,6 +377,23 @@ struct exec_list {
       head = n;
    }
 
+   /**
+    * Remove the first node from a list and return it
+    *
+    * \return
+    * The first node in the list or \c NULL if the list is empty.
+    *
+    * \sa exec_list::get_head
+    */
+   exec_node *pop_head()
+   {
+      exec_node *const n = this->get_head();
+      if (n != NULL)
+	 n->remove();
+
+      return n;
+   }
+
    /**
     * Move all of the nodes from this list to the target list
     */