sql: swap FK masks during altering of space

It was forgotten to swap old and new mask (holding fields involved into
foreign key relation) during space alteration (lists of object
representing FK metadata are swapped successfully). Since mask is vital
and depending on its value different byte-codes implementing SQL query
can be produced, this mistake resulted in assertion fault in debug build
and wrong constraint check in release build. Let's fix this bug and swap
masks as well as foreign key lists.

Closes #4495