To disable tests we carry a patch which allows disabling test by
appending DISABLED to the test function name. Instead just do as
upstream says and prepend the test function so it won't be recognized as
a test any longer.
The docs suggest to prepend x but anything will do. Continue to use
DISABLED_ but as prefix which is actually already in use in one case.
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>