Revert "make sure write_timeout and local_infile ivars are setup to avoid warnings.

This reverts commit e7e43411c5fd3191605b0dfb4d0dfb97c1466561.

I added initializing for ```read_timeout``` because it is used [here](https://github.com/brianmario/mysql2/blob/41f8b327a4029c9dce507eda24d5401891ac5cec/ext/mysql2/client.c#L466). There was case, when that instance variable wasn't initialized and it caused warning.

There is no case where ```write_timeout``` or ```local_infile``` is set into instance variable. There are just writers to set it into mysql via C extension for ```write_timeout``` and ```local_infile```.