build: 0.19 release updates on master
build: 0.19 release updates on master

as per doc/release-process.md.

Note: On branch-off, these same changes should be made on the release branch, with also these additional changes to both files:

  - set `CLIENT_VERSION_REVISION` to `0`
  - set `CLIENT_VERSION_IS_RELEASE` to `true`


Former-commit-id: ac8b9190e00df1455d8fc3351bbfaf9194198068
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin