Add a <flags> tag to the schema file format and a flags='' attribute to
go along with. Add some extra test cases for those.
Add new g_settings_{get,set}_flags() calls and support binding to
GParamSpecFlags properties. Add test cases.
We can't search for a larger needle inside of a smaller haystack, and
unsigned integer subtraction tends to result in very large numbers
rather than small ones.
Add a check for this case and abort out immediately.
Also add a test case (lifted directly from the docs) that demonstrates
the problem.
Issue discovered and tracked down by Milan Bouchet-Valat
