- Chaned min value in mysqld.cc
 - Added testcase to warnings.test


mysql-test/r/warnings.result:
  Added testcase for testing max and min value of max_error_count
mysql-test/t/warnings.test:
  Added testcase for testing max and min value of max_error_count
sql/mysqld.cc:
  Change min value of max_error_count from 1 to 0