Tiny fixes for gnu-nat and another enhancement

[tschwinge]

>Category:       build
>Synopsis:       Tiny fixes for gnu-nat and another enhancement
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Class:          patch
>Submitter-Id:   net
>Originator:     tschwinge@gnu.org
>Release:        HEAD
>Environment:

>Description:
First of all: many thanks to Pedro for the work he has been doing lastly to 
inhibit the gnu-nat target from bit-rotting!  :-)

I will now attach another three tiny patches.
>How-To-Repeat:

>Fix:

>Unformatted: