esp8266: Enable importing of precompiled .mpy files.

esp8266/mpconfigport.h

@@ -9,6 +9,7 @@
 #define MICROPY_ALLOC_PARSE_RULE_INC    (8)
 #define MICROPY_ALLOC_PARSE_RESULT_INC  (8)
 #define MICROPY_ALLOC_PARSE_CHUNK_INIT  (64)
+#define MICROPY_PERSISTENT_CODE_LOAD (1)
 #define MICROPY_EMIT_X64            (0)
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)

py/emitglue.c

@@ -425,7 +425,7 @@ mp_raw_code_t *mp_raw_code_load_file(const char *filename) {
     return rc;
 }
 
-#elif defined(__thumb2__)
+#elif defined(__thumb2__) || defined(__xtensa__)
 // fatfs file reader (assume thumb2 arch uses fatfs...)
 
 #include "lib/fatfs/ff.h"