LOCK kills the server.

Prohibit FLUSH TABLES WITH READ LOCK application to views or
temporary tables.
Fix a subtle bug in the implementation when we actually
did not remove table share objects from the table cache after 
acquiring exclusive locks.

mysql-test/r/flush.result:
  Update results (Bug#51710)
mysql-test/t/flush.test:
  Add a test case for Bug#51710.
sql/sql_parse.cc:
  Fix Bug#51710 "FLUSH TABLES <view> WITH READ LOCK
  killes the server.
  Ensure we don't open views and temporary tables.
  Fix a yet another bug in the implementation which 
  did not actually remove the tables from cache after acquiring
  exclusive locks.