CVE-2026-37460: fix missing input validation in the rfapiRibBi2Ri()
RFP-option parser (bgpd/rfapi/rfapi_rib.c) allowing a bgpd DoS via a
crafted BGP UPDATE with a short or zero-length VNC RFPOPTION subTLV.
Scoped to the rfapi_rib.c hunk of upstream 7676cad6 to match NVD, which
defines this CVE as rfapiRibBi2Ri() only; the same commit's bgp_evpn.c
and bgp_evpn_mh.c hunks belong to CVE-2026-5107 and are not included