bin/Makefile: restrict xbps-uunshare(8) only on linux.
bin/Makefile: restrict xbps-uunshare(8) only on linux.

ebfe/xbps,stpx/xbps,ebfe/xbps,ebfe/xbps,datenwolf/xbps,stpx/xbps,datenwolf/xbps,datenwolf/xbps,stpx/xbps