rocksdb: Update path to dev clang in fbcode
rocksdb: Update path to dev clang in fbcode

Summary: Current clang path in fbcode points to clang 3.5. This diff updates clang path to clang 3.7.

Test Plan:
Make sure clang 3.7 is in use and all tests are passing.
```lang=bash
% USE_CLANG make check
```

Reviewers: meyering, sdong, rven, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34119

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