odb: Fix group removal in region destroy

Since the loop body wasn't changing `_region->groups_` the loop got
stuck on the first element and never progressed past it. This hang can
be reproduced with:

  set block [ord::get_db_block]
  set foo_region  [odb::dbRegion_create $block foo_region]
  set foo_group [odb::dbGroup_create $foo_region foo_group]
  odb::dbRegion_destroy $foo_region

Signed-off-by: Martin Povišer <[email protected]>

Author: povik

src/odb/src/db/dbRegion.cpp

@@ -350,10 +350,8 @@ void dbRegion::destroy(dbRegion* region_)
   dbSet<dbGroup>::iterator gitr;
 
   for (gitr = groups.begin(); gitr != groups.end(); gitr = groups.begin()) {
-    _dbGroup* _group = (_dbGroup*) *gitr;
-    _group->region_ = 0;
-    _group->region_next_ = 0;
-    _group->region_prev_ = 0;
+    dbGroup* group = *gitr;
+    region_->removeGroup(group);
   }
 
   dbProperty::destroyProperties(region);