Move the expected output data from virshdata/*.txt into virshtest.c.

Move the expected output data from virshdata/*.txt into virshtest.c.

* tests/virshtest.c: Embed literal, expected output here, rather than
using virshdata/*.txt file names.
Factor out some common constructs.
(testCompareOutputLit): New function.
(testCompareOutput): #ifdef-out, not that it's unused.
* tests/Makefile.am (SUBDIRS): Remove virshdata/ and all files in it.
* docs/testnode.xml: Fix typo in a comment.
* configure.in (AC_OUTPUT): Remove tests/virshdata/Makefile.