Will return EINVAL for ENV->put_multiple.

Has same semantics as INSERT IGNORE in mysql.
(equivalently) Has same semantics as DB_NOOVERWRITE except that it returns 0 if there is a duplicate key error
instead of DB_KEYEXISTS

git-svn-id: file:///svn/toku/tokudb@17682 c7de825b-a66e-492c-adef-691d508d4ae1