InitClientPrivates() is called on each server reset for the serverClient, from
main.c. This function calls xalloc to allocate memory for the serverClient's
devPrivates field, but the previous contents are not freed.
Solution is to call xrealloc, making sure field is set to NULL the first time in
the InitClient function.
Upon further investigation, the memory is properly freed down at the bottom of
the main function, so memory was not being leaked.