Allow parallel building and testing by using a single Makefile.am
Implement parallel testing using TAP, with various drivers and
compilers living in the build/ directory.
Fix all sorts of issues that this caused, including builddir != srcdir,
leaks in tests and so on.
It would have been nice to break out all the above into separate
commits ... blush.
* 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
