Add tests for auto memballon, implicit IDE, SCSI, virtio channel
controllers, and console/serial back compat.

Additionally, an explicit qemuxml2argvtest for scsi disks is added.
Signed-off-by: NCole Robinson <crobinso@redhat.com>

Only print out '.' for each test case, full test output can be
re-enabled with VIR_TEST_VERBOSE=1, or VIR_TEST_DEBUG=XXXX

Sample output now looks like

  TEST: statstest
        ........................................ 40
        ...................................      75  OK
  PASS: statstest
  TEST: qparamtest
        ................................         32  OK
  PASS: qparamtest
  TEST:
        ............                             12  OK

* tests/capabilityschematest: Define and use $srcdir.
* tests/domainschematest: Likewise.
* tests/interfaceschematest: Likewise.
* tests/networkschematest: Likewise.
* tests/nodedevschematest: Likewise.
* tests/storagepoolschematest: Likewise.
* tests/storagevolschematest: Likewise.

Introduced in commit 39a7be47.

* tests/*schematest: replace 'source' with '.'
* tests/schematestutils.sh: remove 'function' keyword and add '()'

All schema tests have identical functionality, so avoid the duplication.

* tests/Makefile.am (EXTRA_DIST): Distribute domainschemadata/.
* tests/domainschematest: Fail the test if find invocation fails.

  in out of tree builds.
daniel