Call fsync() after modifying /etc/hosts.
Call fsync() after modifying /etc/hosts.

This is a critical file. Breaking it would be very bad. Thus, if the system
crashes before the data is synched to the disk, it should have the complete
file afterwards.

Reviewed-by: iustinp


dimara/ganeti,leshchevds/ganeti,mbakke/ganeti,andir/ganeti,apyrgio/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,grnet/snf-ganeti,leshchevds/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,mbakke/ganeti,onponomarev/ganeti,yiannist/ganeti,dimara/ganeti,yiannist/ganeti,mbakke/ganeti,bitemyapp/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,apyrgio/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,leshchevds/ganeti,ganeti/ganeti,andir/ganeti,ganeti/ganeti