build: remove unused rules: rocksdb_shell, DBClientProxy_test
build: remove unused rules: rocksdb_shell, DBClientProxy_test

Summary:
There were Makefile rules to build those two targets,
but neither rule has worked for a long time, due to missing
dependent source files.  Remove those rules.

Test Plan: run "make"

Reviewers: sdong, ljin, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D33567

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