Add #'slow-query-mipmap-count
Add #'slow-query-mipmap-count

This is a hack, never use it in production code.

GL has no function for querying the number of mipmap levels
so what we do is get the maxiumum possible count and iterate through checking
the width to see at what point the width reaches 0 or GL throws an
error.

bsmr-common-lisp/cepl,djeis97/cepl,cbaggers/cepl