select where .. (col=col and col=col) or ... (false expression)

Problem: optimizer didn't take into account a singular case 
when we eliminated all the predicates at the AND level of WHERE.
That may lead to wrong results.

Fix: replace (a=a AND a=a...) with TRUE if we eliminated all the
predicates.


mysql-test/r/select.result:
  Fix for bug #42957: no results from 
  select where .. (col=col and col=col) or ... (false expression)
    - test result.
mysql-test/t/select.test:
  Fix for bug #42957: no results from 
  select where .. (col=col and col=col) or ... (false expression)
    - test case.
sql/sql_select.cc:
  Fix for bug #42957: no results from 
  select where .. (col=col and col=col) or ... (false expression)
    - replacing equality predicates by multiple equality items check
  if we eliminate all the predicates at the AND level and 
  replace them with TRUE if so.