On unix/linux you pipe it through wc -l
On Windows, I don't know of an equivalent. There are probably some freeware you can get that do the same.
Myself I prefere Perl to do things like this though and works on both platforms...
However, here is an really ugly solution:
mminfo -q "location=lib" -q volrecycle -r volume,pool,family | find /c "tape"
find /c do count lines. So to count lines with find we need some kind of constant on every line since we are really not in to finding stuff but counting. To let it count every line I've added family in the query. Family can be tape or disk. You could always use location instead as a constant or whatever you like. Alright, this is nothing I'm proud of, but it should do the trick...