Removed unnecessary leveldb build rules.
Removed unnecessary leveldb build rules.

After upgraded to leveldb 1.19, the default CXXFLAGS of Mesos conflict
with the require flags when building `db/c_test.c` with clang in macOS.
This patch disables unnecessary rules in leveldb and bypass build
failures in macOS.

Review: https://reviews.apache.org/r/56847/

Gilbert88/mesos,Aman-Jain-14/customizedMesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,chhsia0/mesos,zmalik/mesos,Gilbert88/mesos,abudnik/mesos,neilconway/mesos,asamerh4/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,neilconway/mesos,abudnik/mesos,jpeach/mesos,neilconway/mesos,andschwa/mesos,craimbert/mesos,yuquanshan/customizedMesos,gsantovena/mesos,verizonlabs/mesos,kaysoky/mesos,zmalik/mesos,zmalik/mesos,jpeach/mesos,dforsyth/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,zmalik/mesos,neilconway/mesos,Gilbert88/mesos,reneploetz/mesos,jpeach/mesos,yuquanshan/customizedMesos,craimbert/mesos,dforsyth/mesos,asamerh4/mesos,andschwa/mesos,asamerh4/mesos,gsantovena/mesos,jpeach/mesos,kaysoky/mesos,verizonlabs/mesos,andschwa/mesos,Gilbert88/mesos,andschwa/mesos,abudnik/mesos,asamerh4/mesos,abudnik/mesos,gsantovena/mesos,reneploetz/mesos,abudnik/mesos,reneploetz/mesos,zmalik/mesos,craimbert/mesos,dforsyth/mesos,chhsia0/mesos,Gilbert88/mesos,andschwa/mesos,craimbert/mesos,jpeach/mesos,kaysoky/mesos,verizonlabs/mesos,zmalik/mesos,Gilbert88/mesos,gsantovena/mesos,reneploetz/mesos,chhsia0/mesos,Gilbert88/mesos,dforsyth/mesos,chhsia0/mesos,zmalik/mesos,asamerh4/mesos,craimbert/mesos,andschwa/mesos,neilconway/mesos,neilconway/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,gsantovena/mesos,craimbert/mesos,jpeach/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,reneploetz/mesos,chhsia0/mesos,reneploetz/mesos,abudnik/mesos,kaysoky/mesos,jpeach/mesos,chhsia0/mesos,verizonlabs/mesos,gsantovena/mesos,gsantovena/mesos,verizonlabs/mesos,kaysoky/mesos,asamerh4/mesos,chhsia0/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,verizonlabs/mesos,andschwa/mesos,reneploetz/mesos,abudnik/mesos,verizonlabs/mesos,craimbert/mesos,kaysoky/mesos