py: Make collections module configurable, enabled by default.
diff --git a/py/modcollections.c b/py/modcollections.c
index 11845a0..5278a52 100644
--- a/py/modcollections.c
+++ b/py/modcollections.c
@@ -4,6 +4,8 @@
 #include "obj.h"
 #include "builtin.h"
 
+#if MICROPY_ENABLE_MOD_COLLECTIONS
+
 STATIC const mp_map_elem_t mp_module_collections_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR__collections) },
     { MP_OBJ_NEW_QSTR(MP_QSTR_namedtuple), (mp_obj_t)&mp_namedtuple_obj },
@@ -25,3 +27,5 @@
     .name = MP_QSTR__collections,
     .globals = (mp_obj_dict_t*)&mp_module_collections_globals,
 };
+
+#endif // MICROPY_ENABLE_MOD_COLLECTIONS