netinet/in.h: add IPPROTO_ macros from linux v5.6

add IPPROTO_ETHERNET and IPPROTO_MPTCP, see

  linux commit 2677625387056136e256c743e3285b4fe3da87bb
  seg6: fix SRv6 L2 tunnels to use IANA-assigned protocol number

  linux commit faf391c3826cd29feae02078ca2022d2f912f7cc
  tcp: Define IPPROTO_MPTCP
1 file changed