package/casync: new package

package/casync: new package

Signed-off-by: Yair Ben-Avraham <yairba@protonmail.com>
[yann.morin.1998@free.fr:
  - correctly fix build without lzma in an upstreamable fashion
  - actually fix the build without udev
  - depend on udev, not libudev (which does not exist)
  - don't use += for the first variable assignment to _CONF_OPTS
  - explicitly disable unsupported fuzz options
  - add explicit optiopnal support for bash-completion
  - drop useless comments about "features" and "booleans"
  - fix alphabetical order in DEVELOPERS
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>