Optimize for lp64
Optimize for lp64

Summary:
Some code reorganization in-preparation for replacing with a hardware
instruction.

* Use u64 for some of the key types
* Use an ALIGN macro so code is easier to read

Test Plan: crc32c_test

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D3135

sorphi/rocksdb,OverlordQ/rocksdb,wskplho/rocksdb,RyanTech/rocksdb,jalexanderqed/rocksdb,ylong/rocksdb,bbiao/rocksdb,JackLian/rocksdb,luckywhu/rocksdb,geraldoandradee/rocksdb,tschottdorf/rocksdb,Applied-Duality/rocksdb,wenduo/rocksdb,NickCis/rocksdb,wlqGit/rocksdb,ryneli/rocksdb,SunguckLee/RocksDB,JackLian/rocksdb,vmx/rocksdb,jalexanderqed/rocksdb,IMCG/RcoksDB,wenduo/rocksdb,Vaisman/rocksdb,tsheasha/rocksdb,geraldoandradee/rocksdb,Vaisman/rocksdb,wskplho/rocksdb,alihalabyah/rocksdb,wlqGit/rocksdb,geraldoandradee/rocksdb,JoeWoo/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,norton/rocksdb,NickCis/rocksdb,jalexanderqed/rocksdb,temicai/rocksdb,lgscofield/rocksdb,norton/rocksdb,tizzybec/rocksdb,NickCis/rocksdb,caijieming-baidu/rocksdb,anagav/rocksdb,norton/rocksdb,bbiao/rocksdb,virtdb/rocksdb,kaschaeffer/rocksdb,skunkwerks/rocksdb,SunguckLee/RocksDB,RyanTech/rocksdb,JackLian/rocksdb,tschottdorf/rocksdb,SunguckLee/RocksDB,msb-at-yahoo/rocksdb,lgscofield/rocksdb,amyvmiwei/rocksdb,skunkwerks/rocksdb,tizzybec/rocksdb,mbarbon/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,dkorolev/rocksdb,facebook/rocksdb,anagav/rocksdb,Vaisman/rocksdb,tsheasha/rocksdb,bbiao/rocksdb,wlqGit/rocksdb,SunguckLee/RocksDB,jalexanderqed/rocksdb,facebook/rocksdb,IMCG/RcoksDB,NickCis/rocksdb,lgscofield/rocksdb,facebook/rocksdb,fengshao0907/rocksdb,msb-at-yahoo/rocksdb,vmx/rocksdb,norton/rocksdb,JackLian/rocksdb,msb-at-yahoo/rocksdb,OverlordQ/rocksdb,wenduo/rocksdb,SunguckLee/RocksDB,skunkwerks/rocksdb,luckywhu/rocksdb,luckywhu/rocksdb,skunkwerks/rocksdb,facebook/rocksdb,tsheasha/rocksdb,temicai/rocksdb,IMCG/RcoksDB,wlqGit/rocksdb,tsheasha/rocksdb,Andymic/rocksdb,hobinyoon/rocksdb,wenduo/rocksdb,JohnPJenkins/rocksdb,siddhartharay007/rocksdb,rDSN-Projects/rocksdb.replicated,JoeWoo/rocksdb,tizzybec/rocksdb,temicai/rocksdb,facebook/rocksdb,flabby/rocksdb,Applied-Duality/rocksdb,zhangpng/rocksdb,jalexanderqed/rocksdb,JohnPJenkins/rocksdb,bbiao/rocksdb,wat-ze-hex/rocksdb,Applied-Duality/rocksdb,wat-ze-hex/rocksdb,Applied-Duality/rocksdb,OverlordQ/rocksdb,JackLian/rocksdb,ryneli/rocksdb,tizzybec/rocksdb,wenduo/rocksdb,hobinyoon/rocksdb,caijieming-baidu/rocksdb,virtdb/rocksdb,jalexanderqed/rocksdb,vmx/rocksdb,ylong/rocksdb,dkorolev/rocksdb,virtdb/rocksdb,temicai/rocksdb,Andymic/rocksdb,tschottdorf/rocksdb,IMCG/RcoksDB,siddhartharay007/rocksdb,OverlordQ/rocksdb,dkorolev/rocksdb,anagav/rocksdb,zhangpng/rocksdb,dkorolev/rocksdb,amyvmiwei/rocksdb,Andymic/rocksdb,vashstorm/rocksdb,vmx/rocksdb,Applied-Duality/rocksdb,norton/rocksdb,makelivedotnet/rocksdb,anagav/rocksdb,anagav/rocksdb,flabby/rocksdb,vmx/rocksdb,ylong/rocksdb,flabby/rocksdb,ryneli/rocksdb,IMCG/RcoksDB,fengshao0907/rocksdb,virtdb/rocksdb,JohnPJenkins/rocksdb,bbiao/rocksdb,tizzybec/rocksdb,hobinyoon/rocksdb,tsheasha/rocksdb,siddhartharay007/rocksdb,OverlordQ/rocksdb,tizzybec/rocksdb,wat-ze-hex/rocksdb,dkorolev/rocksdb,ryneli/rocksdb,alihalabyah/rocksdb,zhangpng/rocksdb,caijieming-baidu/rocksdb,mbarbon/rocksdb,makelivedotnet/rocksdb,JackLian/rocksdb,wlqGit/rocksdb,ryneli/rocksdb,norton/rocksdb,biddyweb/rocksdb,JoeWoo/rocksdb,hobinyoon/rocksdb,lgscofield/rocksdb,fengshao0907/rocksdb,makelivedotnet/rocksdb,fengshao0907/rocksdb,NickCis/rocksdb,alihalabyah/rocksdb,siddhartharay007/rocksdb,ryneli/rocksdb,flabby/rocksdb,vmx/rocksdb,skunkwerks/rocksdb,hobinyoon/rocksdb,tsheasha/rocksdb,alihalabyah/rocksdb,JoeWoo/rocksdb,ylong/rocksdb,JoeWoo/rocksdb,jalexanderqed/rocksdb,kaschaeffer/rocksdb,rDSN-Projects/rocksdb.replicated,NickCis/rocksdb,rDSN-Projects/rocksdb.replicated,kaschaeffer/rocksdb,kaschaeffer/rocksdb,sorphi/rocksdb,kaschaeffer/rocksdb,SunguckLee/RocksDB,dkorolev/rocksdb,IMCG/RcoksDB,zhangpng/rocksdb,sorphi/rocksdb,tschottdorf/rocksdb,SunguckLee/RocksDB,JohnPJenkins/rocksdb,alihalabyah/rocksdb,IMCG/RcoksDB,vashstorm/rocksdb,wenduo/rocksdb,caijieming-baidu/rocksdb,caijieming-baidu/rocksdb,tizzybec/rocksdb,siddhartharay007/rocksdb,kaschaeffer/rocksdb,temicai/rocksdb,caijieming-baidu/rocksdb,geraldoandradee/rocksdb,sorphi/rocksdb,facebook/rocksdb,fengshao0907/rocksdb,virtdb/rocksdb,Andymic/rocksdb,wskplho/rocksdb,JohnPJenkins/rocksdb,vashstorm/rocksdb,amyvmiwei/rocksdb,temicai/rocksdb,JohnPJenkins/rocksdb,Applied-Duality/rocksdb,hobinyoon/rocksdb,wskplho/rocksdb,ylong/rocksdb,luckywhu/rocksdb,JoeWoo/rocksdb,biddyweb/rocksdb,lgscofield/rocksdb,Applied-Duality/rocksdb,wskplho/rocksdb,hobinyoon/rocksdb,bbiao/rocksdb,virtdb/rocksdb,msb-at-yahoo/rocksdb,lgscofield/rocksdb,rDSN-Projects/rocksdb.replicated,kaschaeffer/rocksdb,wat-ze-hex/rocksdb,OverlordQ/rocksdb,RyanTech/rocksdb,rDSN-Projects/rocksdb.replicated,tschottdorf/rocksdb,tsheasha/rocksdb,vashstorm/rocksdb,anagav/rocksdb,Andymic/rocksdb,fengshao0907/rocksdb,msb-at-yahoo/rocksdb,amyvmiwei/rocksdb,ylong/rocksdb,msb-at-yahoo/rocksdb,ylong/rocksdb,amyvmiwei/rocksdb,Andymic/rocksdb,wskplho/rocksdb,hobinyoon/rocksdb,biddyweb/rocksdb,Vaisman/rocksdb,bbiao/rocksdb,norton/rocksdb,vmx/rocksdb,temicai/rocksdb,siddhartharay007/rocksdb,amyvmiwei/rocksdb,skunkwerks/rocksdb,amyvmiwei/rocksdb,dkorolev/rocksdb,tsheasha/rocksdb,biddyweb/rocksdb,RyanTech/rocksdb,makelivedotnet/rocksdb,rDSN-Projects/rocksdb.replicated,geraldoandradee/rocksdb,skunkwerks/rocksdb,Andymic/rocksdb,NickCis/rocksdb,fengshao0907/rocksdb,tschottdorf/rocksdb,flabby/rocksdb,zhangpng/rocksdb,biddyweb/rocksdb,geraldoandradee/rocksdb,JoeWoo/rocksdb,mbarbon/rocksdb,virtdb/rocksdb,mbarbon/rocksdb,alihalabyah/rocksdb,flabby/rocksdb,biddyweb/rocksdb,wat-ze-hex/rocksdb,luckywhu/rocksdb,makelivedotnet/rocksdb,RyanTech/rocksdb,Vaisman/rocksdb,wskplho/rocksdb,norton/rocksdb,wlqGit/rocksdb,vmx/rocksdb,biddyweb/rocksdb,luckywhu/rocksdb,JackLian/rocksdb,mbarbon/rocksdb,zhangpng/rocksdb,wenduo/rocksdb,mbarbon/rocksdb,mbarbon/rocksdb,caijieming-baidu/rocksdb,makelivedotnet/rocksdb,wlqGit/rocksdb,facebook/rocksdb,Vaisman/rocksdb,zhangpng/rocksdb,lgscofield/rocksdb,sorphi/rocksdb,OverlordQ/rocksdb,rDSN-Projects/rocksdb.replicated,JohnPJenkins/rocksdb,flabby/rocksdb,vashstorm/rocksdb,RyanTech/rocksdb,facebook/rocksdb,geraldoandradee/rocksdb,luckywhu/rocksdb,makelivedotnet/rocksdb,wat-ze-hex/rocksdb,vashstorm/rocksdb,RyanTech/rocksdb,vashstorm/rocksdb,anagav/rocksdb,alihalabyah/rocksdb,sorphi/rocksdb,ryneli/rocksdb,siddhartharay007/rocksdb,Andymic/rocksdb,sorphi/rocksdb,Vaisman/rocksdb,wenduo/rocksdb