a lookup into a BINARY index by a key ended with spaces. It caused
an assertion abort for a debug version and wrong results for non-debug
versions.

The problem occurred because the function _mi_pack_key stripped off 
the trailing spaces from binary search keys while the function _mi_make_key
did not do it when keys were inserted into the index.

Now the function _mi_pack_key does not remove the trailing spaces from
search keys if they are of the binary type.