Open vSwitch can crash when a flow is deleted

This is not the connection-label leak that landed in the same pull. ## Notes 4e30317ff67a (Ilya Maximets, 2026-08-15). Fix flow mask use-after-free on flow deletion. The mask could be freed while the delete reply was still being built. Short race. Crash. Fixes: 56c19868e115. Cc: stable. Reported as ZDI-CAN-32042. No CVE in the commit. Do not invent one. Also at git.kernel.org/linus. Landed via 91ec20351349 (net-next-7.3). File the child, not the merge. Gitiles lagged this pass. First public visibility was GitHub. Needs datapath control, typically CAP_NET_ADMIN, not an unprivileged login. Class is flow-delete mask RCU UAF. Not the ovs nf_connlabels leak in the same pull.