myloader doesn't close input files on error

Run myloader with input files that can't be imported to mysql. Error messages like these are printed:

** (myloader:12746): CRITICAL **: Error restoring x.y from file x.y-schema.sql~: The used table type doesn't support FULLTEXT indexes

** (myloader:12746): CRITICAL **: Error restoring x.y from file x.y.sql: Table 'x.y' doesn't exist

(Both were generated because there was an x.y~ backup file.)

Notice under /proc/xxx/fd that these two input files are not closed.

It's a really minor bug since the number of parallel threads is kept at the desired value (e.g. in this case there are 6 "normal" files open, rather than 4.)