test/fpos: Fix reading from uninitialized buffer
test/fpos: Fix reading from uninitialized buffer

Fix this:

  ==3054875== Conditional jump or move depends on uninitialised value(s)
  ==3054875==    at 0x109898: test_read (fpos.c:109)
  ==3054875==    by 0x109898: main (fpos.c:243)
  ==3054875==
  ==3054875== Conditional jump or move depends on uninitialised value(s)
  ==3054875==    at 0x10987B: test_read (fpos.c:111)
  ==3054875==    by 0x10987B: main (fpos.c:243)

Link: https://github.com/axboe/liburing/issues/640
Reported-by: Vitaly Chikunov <0d216168d6c4f83410e4fa17a56d762f8c0260fc@altlinux.org>
Signed-off-by: Ammar Faizi <a8266392a329a5c7b5ab982a8996391d75b6438e@gnuweeb.org>
Link: 631854f69c494ef7708e07166e015e209d1b43a8@intel.com
Signed-off-by: Jens Axboe <cd8c6775e60d6f67a6984377324e5290df3d5358@kernel.dk>

axboe/liburing,axboe/liburing,axboe/liburing