py, unix: Allow to compile with -Wunused-parameter.

See issue #699.
diff --git a/py/objcomplex.c b/py/objcomplex.c
index 3af98e4..027292a 100644
--- a/py/objcomplex.c
+++ b/py/objcomplex.c
@@ -49,6 +49,7 @@
 } mp_obj_complex_t;
 
 STATIC void complex_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind) {
+    (void)kind;
     mp_obj_complex_t *o = o_in;
 #if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
     char buf[16];
@@ -76,6 +77,7 @@
 }
 
 STATIC mp_obj_t complex_make_new(mp_obj_t type_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
+    (void)type_in;
     mp_arg_check_num(n_args, n_kw, 0, 2, false);
 
     switch (n_args) {