packet/tcp: Add TCP Control Flags
packet/tcp: Add TCP Control Flags

Add the control flags constants and a helper function to test which
flags are on.

Signed-off-by: Jason Kölker <68c46a606457643eab92053c1c05574abb26f861@koelker.net>
Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

iwaseyusuke/ryu,iwaseyusuke/ryu,TakeshiTseng/ryu,fkakuma/ryu,iwaseyusuke/ryu,pichuang/ryu,fkakuma/ryu,fujita/ryu,pichuang/ryu,Tejas-Subramanya/RYU_MEC,pichuang/ryu,hisaharu/ryu,Tejas-Subramanya/RYU_MEC,hisaharu/ryu,fkakuma/ryu,zangree/ryu,gareging/SDN_Framework,fkakuma/ryu,pichuang/ryu,gareging/SDN_Framework,osrg/ryu,shinpeimuraoka/ryu,osrg/ryu,hisaharu/ryu,osrg/ryu,gareging/SDN_Framework,hisaharu/ryu,pichuang/ryu,zangree/ryu,Tejas-Subramanya/RYU_MEC,fujita/ryu,iwaseyusuke/ryu,osrg/ryu,Tejas-Subramanya/RYU_MEC,Tejas-Subramanya/RYU_MEC,osrg/ryu,fujita/ryu,fujita/ryu,lagopus/ryu-lagopus-ext,zangree/ryu,gareging/SDN_Framework,gareging/SDN_Framework,hisaharu/ryu,lagopus/ryu-lagopus-ext,TakeshiTseng/ryu,lagopus/ryu-lagopus-ext,fkakuma/ryu,zangree/ryu,TakeshiTseng/ryu,lagopus/ryu-lagopus-ext,TakeshiTseng/ryu,zangree/ryu,shinpeimuraoka/ryu,shinpeimuraoka/ryu,lagopus/ryu-lagopus-ext,fujita/ryu,TakeshiTseng/ryu,shinpeimuraoka/ryu,shinpeimuraoka/ryu,iwaseyusuke/ryu