Fix codechecker issues.

answertests.php

backup/moodle2/restore_qtype_stack_plugin.class.php

settings.php

stack/cas/casstring.class.php

stack/cas/connectorhelper.class.php

stack/input/inputbase.class.php

stack/input/textarea/textarea.class.php

tests/answertest_general_cas_test.php

tests/answertestfixtures.class.php

tests/behat/behat_qtype_stack.php

tests/cassession_test.php

tests/casstring_test.php

tests/input_algebraic_test.php

tests/input_textarea_test.php

tests/inputstate_test.php

yui/input/input.js