message: Require CBlockIndex::IsValid() to hold cs_main
diff: @@ -407,7 +407,9 @@ public:
  //! Check whether this block index entry is valid up to the passed validity level.
  bool IsValid(enum BlockStatus nUpTo = BLOCK_VALID_TRANSACTIONS) const
  + EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
  {
  + AssertLockHeld(::cs_main);
  assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
  if (nStatus & BLOCK_FAILED_MASK)
  return false;
  