Backported from Xorg:

  commit f292de2ef13dc994a38029cee9e2642576893332
  Author: Daniel Stone <daniel@fooishbar.org>
  Date:   Wed Mar 21 02:04:12 2007 +0200

    XKB: Fix size_syms calculation bug

    Apparently it needed to be nSyms*15/10, not *12/10; make it match the
        other allocation code.
Backported-to-nx-by: Ulrich Sibiller <uli42@gmx.de>