The GVariant documentation says you can assume that types of no more
than 32 bits may be assumed to be promoted to int by the usual
promotions. If we're going to document that, we should statically
assert that it's true, i.e. sizeof (int) >= sizeof (int32_t).

All reasonable modern platforms are either ILP32 (32-bit platforms),
LP64 (64-bit Linux, *BSD etc.), or LLP64 (64-bit Windows): there have
been ILP64 platforms in the past, but ILP64 has the compelling
disadvantage that {signed char, short, int} can't possibly provide
all of {int8_t, int16_t, int32_t} unless int is 32 bits long.

Bug: https://bugzilla.gnome.org/show_bug.cgi?id=730932


Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: Colin Walters