.gersemirc : add bench dir (#305)

Author: ManifoldFR

.gersemirc

@@ -1,4 +1,4 @@
-definitions: [./CMakeLists.txt, ./bindings, ./cmake, ./examples, ./tests]
+definitions: [./CMakeLists.txt, ./bench, ./bindings, ./cmake, ./examples, ./tests]
 line_length: 80
 indent: 2
 warn_about_unknown_commands: false