Fixing warnings in utils/metadata when building under Windows/Cygwin

Builds under Cygwin and Linux with these changes
OK. Bit caught up at the minute but I'll take a look later and see if it comes in cleanly.

This sort of has a flavour of the next thing I would like to look at which is all the Cygwin platform prototypes which take LONG and so forth, where the Mono code-base seems to be using gint32 and similar. Perhaps a conversation for elsewhere but there must be a sensible (and hopefully straightforward) way of resolving this?