Default to CS_GTOD if CONFIG_CLOCK_GETTIME isn't defined.

Defaulting the clock source to CS_CGETTIME broke on OS X because it
doesn't have clock_gettime. Use CS_GTOD if CONFIG_CLOCK_GETTIME isn't
defined.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove duplicated Windows configure options.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Update the Windows section of the README file.

The 64-bit Windows build instructions can be simplified since Cygwin
includes all the required MinGW64 packages. Also, the pthread DLL is
available as an individual download.

Update the WiX Toolset version to 3.7 and fix the URL since it's no
longer hosted at Sourceforge.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix failure to exit IO loop on some IO sizes

If the size of a file isn't a multiple of the block size being
used, it can cause fio to exit the IO loop, check bytes done,
and then decide to do one more loop since we didn't do quite
as much IO as we wanted to. This happens because the minimum
block size is larger than the remainder. So check for that,
and stop if we need to.

Signed-off-by: Jens Axboe <axboe@kernel.dk>