We could allocate chunks larger than 4GB, but did our
size-accounting in 32-bit values. This could lead to
spurious warnings, inaccurate accounting, and, in
theory, data loss.
  
Affected: 64-bit platforms. Debug-build (with safemalloc).
At least one buffer larger than 4GB. For potential data
loss, a re-alloc on such a buffer would be necessary.


mysys/my_static.c:
  Make memory-accounting 64-bit safe.
mysys/my_static.h:
  Make memory-accounting 64-bit safe.
  Move in struct for better alignment when 64-bit.