xbps-repo-checkvers: added support to check for outdated pkgs in a rootdir.
xbps-repo-checkvers: added support to check for outdated pkgs in a rootdir.

New options:
	-i, --installed [to check for outdated pkgs in a rootdir]
	-r, --rootdir [to set the root directory]

The utility name does not make sense anymore and will be renamed in an
upcoming commit.

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