tests/micropython: Make import_mpy_native test run on all architectures.

Signed-off-by: Damien George <damien@micropython.org>

tests/micropython/import_mpy_native_x64.py → tests/micropython/import_mpy_native.py

-# test importing of .mpy files with native code (x64 only)
+# test importing of .mpy files with native code
 
 try:
     import usys, uio, uos
 
+    usys.implementation._mpy
     uio.IOBase
     uos.mount
 except (ImportError, AttributeError):
     print("SKIP")
     raise SystemExit
 
-if not (usys.platform == "linux" and usys.maxsize > 2**32):
+mpy_arch = usys.implementation._mpy >> 8
+if mpy_arch == 0:
     print("SKIP")
     raise SystemExit
 
@@ -49,15 +51,14 @@ class UserFS:
 
 
 # these are the test .mpy files
+valid_header = bytes([77, 6, mpy_arch, 31])
 # fmt: off
 user_files = {
     # bad architecture
-    '/mod0.mpy': b'M\x06\xfc\x00\x10',
+    '/mod0.mpy': b'M\x06\xfc\x1f',
 
     # test loading of viper and asm
-    '/mod1.mpy': (
-        b'M\x06\x08\x1f' # header
-
+    '/mod1.mpy': valid_header + (
         b'\x02' # n_qstr
         b'\x00' # n_obj
 
@@ -84,9 +85,7 @@ user_files = {
     ),
 
     # test loading viper with additional scope flags and relocation
-    '/mod2.mpy': (
-        b'M\x06\x08\x1f' # header
-
+    '/mod2.mpy': valid_header + (
         b'\x02' # n_qstr
         b'\x00' # n_obj