gen.pl now insists on C: and SPDX-License-Identifier: fields to be present in all files. Closes #9002
Reported-by: Colin Leroy Bug: https://github.com/curl/curl/pull/8503#pullrequestreview-906520081
If a transfer returns an error, using this option makes curl remove the leftover downloded (partial) local file before exiting. Added test 376 to verify Closes #8503