Enable MICROPY_READER_POSIX for file operation.

port/mpconfigport.h

@@ -116,6 +116,8 @@
 #define MICROPY_CPYTHON_COMPAT      (0)
 #define MICROPY_LONGINT_IMPL        (MICROPY_LONGINT_IMPL_MPZ)
 #define MICROPY_FLOAT_IMPL          (MICROPY_FLOAT_IMPL_DOUBLE)
+#define MICROPY_READER_POSIX        (1)
+#define MICROPY_READER_VFS          (0)
 
 // extended modules
 #define MICROPY_PY_UCTYPES          (1)

port/mpy_main.c

@@ -114,9 +114,9 @@ void gc_collect(void) {
     gc_dump_info();
 }
 
-mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
-    mp_raise_OSError(ENOENT);
-}
+//mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
+//    mp_raise_OSError(ENOENT);
+//}
 
 mp_import_stat_t mp_import_stat(const char *path) {
     return MP_IMPORT_STAT_NO_EXIST;