Missing license

[kkofler]

Only the source files v4l2.c and v4l2.h carry license headers (GNU GPL v3 or later). There is no license indication for this package as a whole or for the other individual source files. I can only assume that, since they are being linked together with GPLv3+ code, they are also GPLv3+? The sources should carry a license header or at least a SPDX line. The repository is also missing a copy of the GPLv3.