Allow stack allocating GIBaseInfo, add stack retrieval variants

Allow stack allocating GIBaseInfo, add stack retrieval variants

We don't want to malloc each GIBaseInfo when they can be used in
function invocation; instead, allow stack allocation.

There were a lot of structure typedefs which were actually just
exactly the same as GIBaseInfo, with the one exception of GITypeInfo.

Instead, just put the single GITypeInfo boolean inside GIBaseInfo
as a bit in a bitfield.

GIBaseInfo is still opaque publicly; GIRealInfo is the new
internal structure.

Using this, add new functions to retrieve arguments and argument types
on the stack.

https://bugzilla.gnome.org/show_bug.cgi?id=604074