DB->get on a secondary with flag DB_GET_BOTH will now return EINVAL
instead of crashing on an assert.

Also revamped test_db_get_put_flags to test this, and made all tests run on both
BDB and tokudb

git-svn-id: file:///svn/tokudb@1502 c7de825b-a66e-492c-adef-691d508d4ae1