When $label == "0", $label is not truthy, so if ($label) thinks there isn't
a label. Correct this by looking at the result of the s/// command.
Verified that there are no changes in the .S files created during a normal
build, and that the "0:" labels appear in the translation given in the error
report (and they are the only difference in the before and after output).
Obtained from: OpenSSL commit 9607f5ccf285ac9988a86f95c5ad9f92b556a843