configure: link against geos_c instead of geos
configure: link against geos_c instead of geos

We need geos_c, since we use the C-API, however, geos-config has no
convenient way of actually selecting that library.  We do an ugly sed
replacement instead to make it work.

With this change, I can start mserver5 again without missing symbols.

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