fdisk: sleep-after-sync and fsync usage

fdisk: sleep-after-sync and fsync usage

It seems that sleep() after sync() is unnecessary legacy. It's very
probably unnecessary since kernel 1.3.20. For example the libparted
does not to use sleep() at all.

It seems that more important is fsync() usage in fdisks. For more
details see

  http://marc.theaimsgroup.com/?l=linux-kernel&m=105545785306867&w=3
  http://marc.theaimsgroup.com/?l=linux-kernel&m=105545848607353&w=3
  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=276369

Currently we use fsync() in fdisk only. This patch also add fsync() to
sfdisk and cfdisk.

Addresses: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=276369
Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=502639
Signed-off-by: Karel Zak <kzak@redhat.com>