test_short_dio_read.c: add error handling

Add error handling for open() calls.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
test_sync_io.c: add error handling

Add error handling for open(), posix_memalign() and malloc().
Reuse code for read_* and write_* functions.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Merge pull request #59 from dalgaaf/wip-da-add-errorhandling

add error handling to test_sync_*.c

Reviewed-by: Sage Weil <sage@inktank.com>