close[t:4715] merging 4715 to main. at a high level, ft files are removed by marking OPEN ft/cf's as unlink on close, so when the last reference goes away, the file is unlinked. we log this bit during a checkpoint's fassociate to help with aborting a hot index in the future (so it isn't stricly necessary right now).


git-svn-id: file:///svn/toku/tokudb@44003 c7de825b-a66e-492c-adef-691d508d4ae1