tests: append a newline to expected-output files lacking NL-at-EOF

tests: append a newline to expected-output files lacking NL-at-EOF

* tests/qemuxml2argvtest.c (testCompareXMLToArgvFiles): Adjust the
code that creates "actual" output, so that it too produces a
newline-terminated buffer.
* tests/qemuxml2argvdata/*.args: Append a newline to each, via:
for i in $(find|grep '\.args$'); do echo >> $i;done