Description: ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule
References:
 https://launchpad.net/bugs/1847478
 https://lists.zx2c4.com/pipermail/wireguard/2019-October/004588.html
Notes:
 carnil> Fixes 7d9e5f422150 ("ipv6: convert major tx path to use
 carnil> RT6_LOOKUP_F_DST_NOREF") which was only introduced in 5.3-rc1
 carnil> and not backported to other branches. Intrestingly though the
 carnil> commit was still applied/backported as well in/to 5.2.19.
Bugs:
upstream: released (5.4-rc1) [ca7a03c4175366a92cee0ccc4fec0038c3266e26]
4.19-upstream-stable: N/A "Vulnerable code introduced later"
4.9-upstream-stable: N/A "Vulnerable code introduced later"
3.16-upstream-stable: N/A "Vulnerable code introduced later"
sid: N/A "Vulnerable code introduced later"
4.19-buster-security: N/A "Vulnerable code introduced later"
4.9-stretch-security: N/A "Vulnerable code introduced later"
3.16-jessie-security: N/A "Vulnerable code introduced later"