When a table status is requested by statement like SHOW TABLE
STATUS and there is another statement (e.g. DELETE) sets
number of records to 0 concurrently, we may get division by
zero error, which crashes a server.

This is fixed by using thread local variable x->records instead
of shared info->state->records when we check if it is zero and
divide by it.


myisam/mi_info.c:
  Information schema does not lock a table when it requests table
  state info. If another thread sets info->state->records to 0
  after we check if it is 0 and before we divide by it we may get
  division by zero error.
  
  Check and divide by local x->records variable instead of shared
  info->state->records.