tests: Fix all file ioctl's to support only MP_STREAM_CLOSE.

A return value of 0 from Python-level `ioctl()` means success, but if
that's returned unconditionally it means that the method supports all
ioctl calls, which is not true.  Returning 0 without doing anything can
potentially lead to a crash, eg for MP_STREAM_SEEK which requires returning
a value in the passed-in struct pointer.

This commit makes it so that all `ioctl()` methods respond only to
MP_STREAM_CLOSE, ie they return -1 (indicating error) for all other ioctl
calls.

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

tests/run-tests.py

@@ -68,7 +68,9 @@ class __File(io.IOBase):
     sys.modules['__injected_test'].__name__ = '__main__'
     self.off = 0
   def ioctl(self, request, arg):
-    return 0
+    if request == 4: # MP_STREAM_CLOSE
+      return 0
+    return -1
   def readinto(self, buf):
     buf[:] = memoryview(__buf)[self.off:self.off + len(buf)]
     self.off += len(buf)