configure: Use default error message when package is missing
    
    To make clear why configure failed - e.g.:
     Package requirements (spice-client-gtk-2.0 >= 0.28) were not met
     Requested 'spice-client-gtk-2.0 >= 0.28' but version of spice-client-gtk-2.0 is 0.25
    instead of
     spice-gtk requested but not found
    
    Related:
    https://bugzilla.redhat.com/show_bug.cgi?id=1214577