mcproxy: remove this package

Upstream [1] looks dead. The latest commit was pushed 7 years ago.
Pull requests are not reviewed so far [2].

[1] https://github.com/mcproxy/mcproxy
[2] mcproxy/mcproxy#18

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>

Author: BKPepe