Updated the sqlparser fuzzer to use the latest version of the sqlparser library.
Updated the sqlparser fuzzer to use the latest version of the sqlparser library.

Specifically:
* Fixed the issues related to API changes.
* Changed to using the ParseNext() API (which can parse multiple statements).
* Changed to use the io.Reader interface.
* Added a class to artificially reduce the chunks that can be read, to increase the chance of buffer underrun/overrun errors.

dgryski/go-fuzz,dgryski/go-fuzz