Problem: we believe a number cannot start with '-' ['+'] sign reading rows.

Fix: let field->store() check given values.


mysql-test/r/csv.result:
  Fix for bug #29353: inserting a negative value to a csv table leads to the table corruption
    - test result.
mysql-test/t/csv.test:
  Fix for bug #29353: inserting a negative value to a csv table leads to the table corruption
    - test case.
storage/csv/ha_tina.cc:
  Fix for bug #29353: inserting a negative value to a csv table leads to the table corruption
    - code optimization: removed unnecessary file_buff->get_value() calls.
    - let field->store() check given value correctness.