[ros-kernel] Unnecessary relinks triggered by regtests

[Thomas Weidenmueller]

Ge van Geldorp wrote:

>Components which have "TARGET_REGTESTS = yes" in their Makefile will
>currently relink on every make, even if nothing changed at all. The
>attached patch fixes that. Does anyone have objections against it?
>
>Gé van Geldorp.
>  
>
go ahead and commit, these relinks are really bugging me, especially 
when doing debug builds...

Regards
Thomas