Accessing a file that is bigger than 2G may report that read/write operation
failed. This may affect anything that uses my_pread/my_pwrite functions, e.g.
MyISAM, ARCHIVE, binary log.

For MyISAM INSERT may report that table is crashed when writing to a table
that is bigger than 2G.

This is fixed by using proper offset type in my_pread/my_pwrite functions on
systems that do not have native pread/pwrite calls.

Affects systems that do not have native pread/pwrite calls, e.g. Windows.

No test case for this fix, since it requires huge table.