lib/package_conflicts.c: do not add dups unnecessarily.
lib/package_conflicts.c: do not add dups unnecessarily.

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