Request for review: do not use --sync with df during sanity check

[Omair Majid]

Hi,

Can someone please review the following webrev?

http://cr.openjdk.java.net/~omajid/webrevs/no-sync/01/

It modifies the sanity check (under linux) to use df without --sync when 
it computes the free space. This is what is done in the solaris case. 
The accuracy gained by using --sync is probably not worth the 
performance loss caused by flushing disk buffers.

The patch was originally written by Andrew John Hughes 
(ahughes at redhat.com) and we have had this in icedtea6 for almost a year now.

Thanks,
Omair