refs #5710 add accounting for flush count, number of bytes, IO time (stored as tokutime, shown in seconds), uncompressed size, and compressed size. also add these stats for when the logger writes to disk (os_pwrite, not fsync)


git-svn-id: file:///svn/toku/tokudb@50513 c7de825b-a66e-492c-adef-691d508d4ae1