build: Remove *.tar.xz on make clean
build: Remove *.tar.xz on make clean

Since some version of the build utilities, .tar.xz-files containing the
source files are created when building the Debian packages. Update the
Makefile to remove also those files when performing the clean action.

SpriteLink/NIPAP,garberg/NIPAP,bbaja42/NIPAP,garberg/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,garberg/NIPAP,bbaja42/NIPAP,garberg/NIPAP,SpriteLink/NIPAP,garberg/NIPAP,garberg/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP