libxbps: make xbps_*_find_virtualpkg_*_by_name funcs work as expected.
libxbps: make xbps_*_find_virtualpkg_*_by_name funcs work as expected.

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