Problem: long and long long types mess in a comparison may lead to wrong results on some platforms.
Fix: prefer [unsigned] long long as [u]longlong as it's used unconditionally in many places.


include/my_global.h:
  Fix for bug #29079: Semantics of "bigint" depend on platform specifics (size, signedness of char ?)
    - use [unsigned] long long as [u]longlong if sizeof(long long) == 8, to avoid type mess,
      as we use [unsigned] long long unconditionally in many places, for example in constants 
      with [U]LL suffix.