restore original 'lex->query_tables' table list after
   processing of information schema table
   remove unnecessary operations


mysql-test/r/ps.result:
  Fix for bug#9383: INFORMATION_SCHEMA.COLUMNS, JOIN, Crash, prepared statement
mysql-test/t/ps.test:
  Fix for bug#9383: INFORMATION_SCHEMA.COLUMNS, JOIN, Crash, prepared statement
sql/sql_lex.h:
  Fix for bug#9383: INFORMATION_SCHEMA.COLUMNS, JOIN, Crash, prepared statement
sql/sql_show.cc:
  Fix for bug#9383: INFORMATION_SCHEMA.COLUMNS, JOIN, Crash, prepared statement