examples: fix 64-bit integer formatting on Windows

The Windows printf functions don't support %llu/%lld for printing 64-bit
integers. For most of libvirt this doesn't matter as we rely on gnulib
which provides a replacement printf that is sane.

The example code is designed to compile against the normal OS headers,
with no use of gnulib and thus has to use the platform specific printf.
To deal with this we must use the macros PRI* macros from inttypes.h
to get the platform specific format string.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>