[PATCH] kexec: use _DEFAULT_SOURCE instead to remove compiling warning

[Simon Horman]

On Thu, Aug 06, 2015 at 07:10:55PM +0800, Baoquan He wrote:
> Now compiling will print warning like below. Change code as it suggested.
>  # warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"
>    ^
> 
> Signed-off-by: Baoquan He <bhe at redhat.com>

Thanks, applied.