Merge 2.2.0 scheduling statistics to 3.0.0 (#2075).
Restore #2094 fix to 3.0.0 (cachefiles_lock).
Command line for merge (executed in tokudb.2037b, ../tokudb.2.2.0 is local sandbox image of 2.2.0 release): svn merge -r14900:HEAD ../tokudb.2.2.0

git-svn-id: file:///svn/toku/tokudb.2037b@15629 c7de825b-a66e-492c-adef-691d508d4ae1