py: Add #if guard around gc-specific code.

py/runtime.c

@@ -1208,11 +1208,15 @@ mp_obj_t mp_parse_compile_execute(mp_lexer_t *lex, mp_parse_input_kind_t parse_i
 
 void *m_malloc_fail(size_t num_bytes) {
     DEBUG_printf("memory allocation failed, allocating " UINT_FMT " bytes\n", num_bytes);
-    if (gc_is_locked()) {
-        nlr_raise(mp_obj_new_exception_msg(& mp_type_MemoryError, 
+    if (0) {
+        // dummy
+    #if MICROPY_ENABLE_GC
+    } else if (gc_is_locked()) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_MemoryError,
                                            "memory allocation failed, heap is locked"));
+    #endif
     } else {
-        nlr_raise(mp_obj_new_exception_msg_varg(& mp_type_MemoryError, 
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_MemoryError,
                                                 "memory allocation failed, allocating " UINT_FMT " bytes", num_bytes));
     }
 }