Fix T102670: Crash after deleting attribute in edit mode

Since we free BMesh attributes by attempting on every domain,
sometimes the attribute wouldn't be found for a CustomData.
We avoid reallocating custom data blocks in that case, so we
need to pass the ownership of the "pool" back to the BMesh.

source/blender/bmesh/intern/bmesh_interp.c

@@ -907,6 +907,10 @@ bool BM_data_layer_free_named(BMesh *bm, CustomData *data, const char *name)
   if (has_layer) {
     update_data_blocks(bm, &olddata, data);
   }
+  else {
+    /* Move pool ownership back to BMesh CustomData, no block reallocation. */
+    data->pool = olddata.pool;
+  }
 
   if (olddata.layers) {
     MEM_freeN(olddata.layers);