pgsql: Copy fsync() defines into test_fsync.c, someday place them in an

Log Message:
-----------
Copy fsync() defines into test_fsync.c, someday place them in an
include.

Propery align for O_DIRECT.

Check for write()/fsync() failures.

Modified Files:
--------------
pgsql/src/tools/fsync:
test_fsync.c (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tools/fsync/test_fsync.c.diff?r1=1.16&r2=1.17)