geom: fixed mbroverlaps()
geom: fixed mbroverlaps()

- use proper signature / argument types,
  i.e., **mbr instead of *mbr
- use correct logic to detect overlap

(Credits go to Thibault Sellam for detecting the bug
 and providing the correct logic.)

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb