stream_vcd.c: fix compilation on win32

the mp_vcd_priv_t doesn't have a file descriptor but a file handle on
win32.
Merge branch 'vcd' into all_merged

* vcd:
  stream_vcd.c: fix compilation on win32
Merge branch 'all_merged' into all_merged_with_lua

* all_merged:
  stream_vcd.c: fix compilation on win32