lib: ignore oid_registry_data.c file

The file is generated by scripts/build_OID_registry based on the
include/linux/oid_registry.h file.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
diff --git a/lib/.gitignore b/lib/.gitignore
new file mode 100644
index 0000000..72ff0e9
--- /dev/null
+++ b/lib/.gitignore
@@ -0,0 +1 @@
+oid_registry_data.c