number of seconds (which can include microseconds). (Bug #6760)


mysql-test/r/func_misc.result:
  Add new results
mysql-test/t/func_misc.test:
  Add new regression test.
sql/item_create.cc:
  Add create_func_sleep()
sql/item_create.h:
  Add create_func_sleep()
sql/item_func.cc:
  Add sleep() implementation
sql/item_func.h:
  Add class for sleep() function
sql/lex.h:
  Handle SLEEP() function