xbps_transaction_prepare: check for unresolved shlibs a bit early.
xbps_transaction_prepare: check for unresolved shlibs a bit early.

It's just better if we check for unresolved shlibs earlier because
the transaction array will be smaller if there are replaced packages.

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