malformed output for VARCHAR fields containing null terminators

[James King]

If a string in a VARCHAR field has \x00, the output from constraints_parser for that row will be malformed; the field will be truncated at the null terminator, and no closing quote will be added, messing up all following fields in the row.

[James King (t-james-king)]

The print_string() function in print_data.c handles the escaping of backslashes, double quotes, tabs, and LF/CR, but not null characters. The attached patch appears to fix the issue.

Looking at the Special Character Escape Sequences table at http://dev.mysql.com/doc/refman/5.0/en/string-literals.html, ASCII 26 may also need to be escaped in the same fashion if the resulting output will be loaded on a Windows machine. The other special characters do not appear to be relevant in a LOAD DATA INFILE context.