[PATCH mtd-utils] fix build warnings w/newer glibc & _BSD_SOURCE

[Brian Norris]

On Sat, Apr 16, 2016 at 10:11:51PM -0400, Mike Frysinger wrote:
> The _BSD_SOURCE define has been deprecated for a while now.  Instead,
> code should be defining _DEFAULT_SOURCE.  By defining both, it'll work
> with both new & old versions warning-free.
> 
> Signed-off-by: Mike Frysinger <vapier at gentoo.org>

Pushed to mtd-utils.git