networkxml2conftest: Allow regenerating more in one run

networkxml2conftest: Allow regenerating more in one run

Currently, there are two calls to virTestCompareToFile() inside
of testCompareXMLToConfFiles(). If the first one fails the
control jumps directly onto the fail label and skips the second
one. This means that When regenerating test case output
(VIR_TEST_REGENERATE_OUTPUT) the test binary has to be called
twice to regenerate all the files. Suboptimal. Try harder to call
both compare helpers.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>