message: Improve CCTEEqual()
  We do not need to call FSubset() twice to check for equality.
  Two CTE requirements will be considered equal if their lengths match and
  one is subset of the other.
diff: @@ -170,7 +170,7 @@ namespace gpopt
  const
  {
  GPOS_ASSERT(NULL != pcter);
  - return this->FSubset(pcter) && pcter->FSubset(this);
  + return (m_phmcter->UlEntries() == pcter->m_phmcter->UlEntries()) && this->FSubset(pcter);
  }
  // check if current requirement is a subset of the given one
  