py: Allow to disable array module and bytearray type.

array.array and bytearray share big deal of code, so to get real savings,
both need to be disabled.
diff --git a/py/objarray.c b/py/objarray.c
index 05821e8..b13df2b 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -37,6 +37,8 @@
 #include "runtime.h"
 #include "binary.h"
 
+#if MICROPY_PY_ARRAY || MICROPY_PY_BUILTINS_BYTEARRAY
+
 typedef struct _mp_obj_array_t {
     mp_obj_base_t base;
     machine_uint_t typecode : 8;
@@ -310,3 +312,5 @@
     o->cur = 0;
     return o;
 }
+
+#endif // MICROPY_PY_ARRAY || MICROPY_PY_BUILTINS_BYTEARRAY