This unifies the test scripts to all use the similar pattern added for
schematests in ace4aecd. This gives the following

- Enables running all tests from outside of tests/ dir
- Drops redundant abs_* definitions, which are set by test-lib.sh
- Drops unnecessary srcdir variable which was only used for sourcing
    test-lib.sh

Behavior changes:

- srcdir can no longer be overwritten, but I don't know why anyone would
    really need to...
- Script VERBOSE setting no longer prints commands executed by test-lib.sh.
    if anyone cares I suggest handling this in test-lib.sh which already
    has other verbose style handling

Previously it failed like:

$ ./tests/domainschematest
./tests/domainschematest: line 4: ./test-lib.sh: No such file or directory

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