Apart from having more developer-friendly messages if the assertions go
wrong, it also prevents the assertions not being run if
`G_DISABLE_ASSERT` is defined (e.g. for performance reasons).
Don't try to use G_IS_OBJECT() to see if an object was finalized
as this segfaults in corner cases, even with our crafty check
for a pointer within our memory space.
https://bugzilla.gnome.org/show_bug.cgi?id=705202
* Cleanup secure memory allocator for valgrind.
* Bring valgrind headers in.
* Add lots of suppressions for glib, gdbus, gcrypt
* Fix up a bunch of bugs where things weren't getting freed
* Add new 'make check-memory' target
