Analysis: fil_extend_space_to_desired_size() does not provide file
node to os_aio(). This failed on Windows only because on Windows
we do not use posix_fallocate() to extend file space.

Fix: Add file node to os_aio() function call and make sure that
we do not use NULL pointer at os_aio_array_reserve_slot(). Additionally,
make sure that we do not use 0 as file_block_size (512 is the minimum).