cachefile openfd_mutex is gone
also clarified an error condition in ft_open
git-svn-id: file:///svn/toku/tokudb@43730 c7de825b-a66e-492c-adef-691d508d4ae1
simplified how reserving filenums works.
no more tracking reserved filenums in an OMT. just give out an autoincrement value and be sure that it isn't already used by something that exists in the cachetable.
git-svn-id: file:///svn/toku/tokudb@43729 c7de825b-a66e-492c-adef-691d508d4ae1