dcpomatic/test/encryption_test.cc, branch compose

dcpomatic/test/encryption_test.cc, branch compose DCP-o-matic DCP tools https://git.carlh.net/cgit/dcpomatic/atom?h=compose 2021-05-27T12:27:22Z Bump libdcp for fix to decryption of SMPTE subtitles. 2021-05-27T12:27:22Z Carl Hetherington cth@carlh.net 2021-05-27T12:27:22Z urn:sha1:bb89ec4a3d7a912f1f79e8b13ec9f1be5481ca96 Also add a test for that.