fix comments / add BACKPRESSURE_READS compile time option
fix comments / add BACKPRESSURE_READS compile time option

git-svn-id: 459970da87506910ac315916d0f5985452181198@3773 8dad8b1f-cf64-0410-95b6-bcf113ffbcfe

sears/bLSM,sears/bLSM,sears/bLSM