This is an API break, but it should not affect third party code since
that code should not be interacting with the `data` member in a way that
invokes its `volatile` qualifier (such as copying to an intermediate
variable).

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #600

All gobject/*.{c,h} files have been processed.

gmarshal.c and gmarshal.h don't have a license header.

https://bugzilla.gnome.org/show_bug.cgi?id=776504

gcc has optimizations for include guards that only work
if they are outermost in the the header.
https://bugzilla.gnome.org/show_bug.cgi?id=689810

This adds supports for a lock-less a non-shrinking growable array.
You can use it to do reads using no locks, as long as your read-code
can handle that during the read transaction the object can be modified
by another writer (but it will not change size or be freed), and you
can only trust the result once the transaction has finished successfully.

This doesn't free things like RCU normally does, instead it pushes the
memory on a free list that is reused for other atomic arrays.