added code to exit a tool if the forced config file wasn't found

per-file comments:
  client/mysql.cc
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  client/mysql_upgrade.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  client/mysqladmin.cc
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  client/mysqlcheck.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  client/mysqldump.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  client/mysqlimport.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  client/mysqlshow.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  client/mysqlslap.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  mysql-test/t/mysql.test
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
   test added
  sql/mysqld.cc
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  storage/myisam/myisamchk.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found
  storage/myisam/myisampack.c
Bug#47216      programs should quit if the file specified by --defaults-file option isn't found
    added code to exit a tool if the forced config file wasn't found